View source for Sapphire

{{Short description|Gem variety of corundum}}
{{Other uses}}
[[File:Szafir - Ratnapura, Sri Lanka.jpg|thumb|Sapphire - Ratnapura, Sri Lanka.]]
{{Use American English|date=June 2019}}
{{Use dmy dates|date=March 2024}}
{{Infobox mineral
| boxbgcolor    = #4a5fe7
| boxtextcolor  = #ffffff
| name          = Sapphire
| category      = [[Oxide mineral]]
| image         = Logan Sapphire 10956420 cropped.png
| imagesize     = 
| caption       = The 423-[[Carat (mass)|carat]] (85 g) blue [[Logan Sapphire]]
| formula       = [[Aluminium oxide]], [[aluminium|Al]]<sub>2</sub>[[oxygen|O]]<sub>3</sub>
| molweight     = 
| system        = [[Trigonal]]
| class         = Hexagonal scalenohedral ({{overline|3}}m) <br/>[[H-M symbol]]: ({{overline|3}}2/m)
| symmetry      = ''R''{{overline|3}}c
| color         = Typically blue, but varies
| habit         = As crystals, massive and granular
| twinning      = Both growth twins (in various orientations) and polysynthetic glide twinning on the rhombohedron [10{{overline|1}}1
| cleavage      = Poor
| fracture      = Conchoidal, splintery
| mohs          = 9.0
| luster        = Vitreous
| refractive    = ''n''<sub>ω</sub> = 1.768–1.772 <br/>''n''<sub>ε</sub> = 1.760–1.763
| birefringence = 0.008
| opticalprop   = Uniaxial (–), [[Abbe number]] 72.2
| pleochroism   = Strong
| streak        = Colorless
| gravity       = 3.98–4.06
| density       = 
| melt          = 2,030–2,050 °C
| fusibility    = Infusible
| diagnostic    = 
| solubility    = Insoluble
| diaphaneity   = Transparent to nearly opaque
| other         = [[Coefficient of thermal expansion]] (5.0–6.6){{e|−6}}/K {{citation needed|date=August 2021}}<br/>
[[relative permittivity]] at 20 °C <br/>ε = 8.9–11.1 (anisotropic)<ref name="Harman-1994">
{{cite journal |doi = 10.1063/1.357922 |title=Optical constants of sapphire (alpha-Al2O3) single crystals |year=1994 |last1=Harman |first1=Alang Kasim |last2=Ninomiya |first2=Susumu |last3=Adachi |first3=Sadao |journal=Journal of Applied Physics |volume=76 |issue=12 |pages=8032–8036 |bibcode=1994JAP....76.8032H}}</ref>
}}
[[File:Saphir gisements.jpg|thumb|upright=1.25|Main sapphire-producing countries]]

<!-- It has been established that this article will be written in ''American English'', with official names such as "aluminium" from the IUPAC spelled accordingly. -->
'''Sapphire''' is a precious [[gemstone]], a variety of the mineral [[corundum]], consisting of [[aluminium oxide]] ({{nowrap|α-[[aluminium|Al]]<sub>2</sub>[[Oxygen|O]]<sub>3</sub>}}) with trace amounts of elements such as [[iron]], [[titanium]], [[cobalt]], [[lead]], [[chromium]], [[vanadium]], [[magnesium]], [[boron]], and [[silicon]]. The name ''sapphire'' is derived from the Latin word ''{{linktext|sapphirus}}'', itself from the [[Greek language|Greek]] word {{Transliteration|grc|sappheiros}} ({{lang|grc|{{linktext|σάπφειρος}}}}), which referred to [[lapis lazuli]].<ref>{{Cite web|url=http://www.perseus.tufts.edu/hopper/morph?l=sapfeiros&la=greek#lexicon|title=Greek Word Study Tool|website=www.perseus.tufts.edu|access-date=5 December 2022|archive-date=5 December 2022|archive-url=https://web.archive.org/web/20221205213713/http://www.perseus.tufts.edu/hopper/morph?l=sapfeiros&la=greek#lexicon|url-status=live}}</ref> It is typically blue, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors. Red corundum stones also occur, but are called [[ruby|rubies]] rather than sapphires.<ref name="GIA-2">{{Cite web|url=http://www.gia.edu/sapphire|title=Sapphire|work=GIA|publisher=Gemological Institute of America Inc.|access-date=27 October 2016|archive-date=30 October 2016|archive-url=https://web.archive.org/web/20161030075103/http://www.gia.edu/sapphire|url-status=live}}</ref> Pink-colored corundum may be classified either as ruby or sapphire depending on the locale. Commonly, natural sapphires are cut and polished into gemstones and worn in [[jewellery|jewelry]]. They also may be created synthetically in laboratories for industrial or decorative purposes in large [[boule (crystal)|crystal boules]]. Because of the remarkable [[hardness]] of sapphires{{snd}} 9 on the [[Mohs scale of mineral hardness|Mohs scale]] (the third-hardest mineral, after [[diamond]] at 10 and [[moissanite]] at 9.5){{snd}} sapphires are also used in some non-ornamental applications, such as [[infrared]] [[optics|optical]] components, high-durability [[window]]s, [[watch|wristwatch]] crystals and movement bearings, and very thin [[wafer (electronics)|electronic wafer]]s, which are used as the [[insulator (electricity)|insulating]] [[Substrate (materials science)|substrate]]s of special-purpose [[solid-state electronics]] such as integrated circuits and [[gallium nitride|GaN]]-based blue [[light-emitting diode|LEDs]].

==Natural sapphires==
[[File:LgYellowSapphire.jpg|thumb|left|An uncut, rough yellow sapphire found at the Spokane Sapphire Mine near [[Helena, Montana]]]]

Sapphire is one of the two gem-varieties of [[corundum]], the other being [[ruby]] (defined as corundum in a shade of red). Although blue is the best-known sapphire color, it occurs in other colors, including gray and black, and also can be colorless. A pinkish orange variety of sapphire is called [[#Padparadscha|padparadscha]].

Significant sapphire deposits are found in [[Australia]], [[Afghanistan]], [[Cambodia]], [[Cameroon]], [[China]] ([[Shandong]]), [[Colombia]], [[Ethiopia]], [[India]] ([[Jammu and Kashmir (union territory)|Jammu and Kashmir]]), [[Kenya]], [[Laos]], [[Madagascar]], [[Malawi]], [[Mozambique]], [[Myanmar]] ([[Burma]]), [[Nigeria]], [[Rwanda]], [[Sri Lanka]], [[Tanzania]], [[Thailand]], [[United States]] ([[Montana]]) and [[Vietnam]].<ref name="Hughes-2017">{{cite book | first1=Richard W. | last1=Hughes| first2=Wimon| last2=Manorotkul| first3=E. Billie| last3=Hughes| title = Ruby & Sapphire: A Gemologist's Guide | year=2017 | publisher = RWH Publishing/Lotus Publishing | isbn = 978-0-9645097-1-9}}</ref>{{rp|431–707}} Sapphire and rubies are often found in the same geographical settings, but they generally have different geological formations. For example, both ruby and sapphire are found in Myanmar's Mogok Stone Tract, but the rubies form in marble, while the sapphire forms in granitic pegmatites or corundum syenites.<ref name="Hughes-2017"/>{{rp|403–429}}

Every sapphire mine produces a wide range of quality, and origin is not a guarantee of quality. For sapphire, Jammu and Kashmir receives the highest premium, although Burma, Sri Lanka, and Madagascar also produce large quantities of fine quality gems.<ref name="GIA-2"/>

The cost of natural sapphires varies depending on their color, clarity, size, [[Cut (gems)|cut]], and overall quality. Sapphires that are completely untreated are worth far more than those that have been treated. Geographical origin also has a major impact on price. For most gems of one [[Carat (mass)|carat]] or more, an independent report from a respected laboratory such as [[Gemological Institute of America|GIA]], [[Lotus Gemology]], or [[SSEF]], is often required by buyers before they will make a purchase.<ref name="Lotus">{{cite web| title=Gem Testing Labs • Tips on Choosing a Colored Gem Testing Lab| url=https://www.lotusgemology.com/index.php/library/articles/452-gem-testing-labs-tips-on-choosing-a-gem-testing-lab-lotus-gemology| work=Lotus Gemology| publisher=Lotus Gemology Co. Ltd.| access-date=5 November 2019| archive-date=5 November 2019| archive-url=https://web.archive.org/web/20191105033754/https://www.lotusgemology.com/index.php/library/articles/452-gem-testing-labs-tips-on-choosing-a-gem-testing-lab-lotus-gemology| url-status=live}}</ref>

==Colors==
Sapphires in colors other than blue are called "fancy" sapphires. "Parti sapphire" is used for multicolor stones with zoning of different colors (hues), but not different shades.<ref>{{Cite book|url=https://books.google.com/books?id=7BvyAAAAMAAJ&q=Sapphires+in+colors+other+than+blue+called+fancy+or+parti+colored&pg=PA605|title=The Mineral Industry|date=1921|publisher=Scientific Publishing Company|language=en|access-date=6 October 2020|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323110126/https://books.google.com/books?id=7BvyAAAAMAAJ&q=Sapphires+in+colors+other+than+blue+called+fancy+or+parti+colored&pg=PA605#v=snippet&q=Sapphires%20in%20colors%20other%20than%20blue%20called%20fancy%20or%20parti%20colored&f=false|url-status=live}}</ref>

Fancy sapphires are found in yellow, orange, green, brown, purple, violet, and practically any other hue.<ref name=GIA>{{Cite web|url=http://www.gia.edu/sapphire-description|title=Sapphire Description|website=GIA|publisher=Gemological Institute of America Inc.|access-date=21 June 2016|archive-date=2 July 2016|archive-url=https://web.archive.org/web/20160702112203/http://www.gia.edu/sapphire-description|url-status=live}}</ref>

Gemstone color can be described in terms of [[hue]], [[Colorfulness|saturation]], and [[Lightness (color)|tone]]. Hue is commonly understood as the "[[color]]" of the gemstone. Saturation refers to the vividness or brightness of the hue, and tone is the lightness to darkness of the hue.<ref name="Hughes-2017"/>{{rp| 333–401}}

===Blue sapphire===
{{redirect|Blue Sapphire|the cruise ship|Blue Sapphire (ship)|the horse race|Blue Sapphire Stakes}}
[[File:Geschliffener blauer Saphir.jpg|thumb|upright|Teardrop-shaped blue sapphire]]

Blue sapphire exists in various mixtures of its primary (blue) and secondary hues, various tonal levels (shades) and at various levels of saturation (vividness).

Blue sapphires are evaluated based upon the purity of their blue hue. [[Violet (color)|Violet]] and [[green]] are the most common secondary hues found in blue sapphires.<ref name="Hughes-2017"/>{{rp|333–401}} The highest prices are paid for gems that are pure blue and of vivid saturation. Gems that are of lower saturation, or are too dark or too light in tone are of less value. However, color preferences are a personal taste.<ref name="Hughes-2017"/>{{rp| 333–401}}

The {{convert|423|carat|adj=on}} [[Logan sapphire]] in the [[National Museum of Natural History]], in [[Washington, D.C.]], is one of the largest [[facet]]ed gem-quality blue sapphires in existence.[[File:Sapphire III cropped flash.jpg|thumb|left|Dark blue sapphire, probably of Australian origin, showing the brilliant surface luster typical of faceted corundum gemstones]]

===Parti sapphires===

Particolored sapphires (or bi-color sapphires) are those stones that exhibit two or more colors within a single stone.<ref name=GIA/> The desirability of particolored or bi-color sapphires is usually judged based on the zoning or location of their colors, the colors' saturation, and the contrast of their colors.<ref name="International Gem Society">{{Cite web |title=Parti Sapphires: the Colored Gemstones for 2021 |url=https://www.gemsociety.org/article/parti-sapphires-the-colored-gemstones-for-2021/ |access-date=20 May 2021 |website=International Gem Society |language=en |archive-date=20 May 2021 |archive-url=https://web.archive.org/web/20210520002707/https://www.gemsociety.org/article/parti-sapphires-the-colored-gemstones-for-2021/ |url-status=live }}</ref> Australia is the largest source of particolored sapphires; they are not commonly used in mainstream jewelry and remain relatively unknown. Particolored sapphires cannot be created synthetically and only occur naturally.<ref name="International Gem Society" />

===Pink sapphires===
[[File:Pink sapphire ring.jpg|thumb|Pink sapphire]]
Pink sapphires occur in shades from light to dark pink, and deepen in color as the quantity of [[chromium]] increases. The deeper the pink color, the higher their [[monetary value]]. In the United States, a minimum color saturation must be met to be called a [[ruby]], otherwise the stone is referred to as a ''pink sapphire''.<ref name="Matlins-2010">{{cite book|url=https://books.google.com/books?id=4UANp6MCTSQC|title=Colored Gemstones|last=Matlins|first=Antoinette Leonard|publisher=Gemstone Press|year=2010|isbn=978-0-943763-72-9|page=203|access-date=3 March 2016|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323110126/https://books.google.com/books?id=4UANp6MCTSQC|url-status=live}}</ref>

===Padparadscha===
[[File:Padparadscha sapphire.jpg|thumb|Faceted padparadscha]]

''Padparadscha'' is a delicate, light to medium toned, pink-orange to orange-pink hued [[corundum]], originally found in [[Sri Lanka]],<ref>{{cite web | url=http://www.lazarosoho.com/Properties-of-Sapphire-Jewelry_b_55.html | title=Properties of Sapphire | publisher=Lazaro SoHo | access-date=25 November 2014 | archive-date=6 March 2016 | archive-url=https://web.archive.org/web/20160306094408/http://www.lazarosoho.com/Properties-of-Sapphire-Jewelry_b_55.html | url-status=live }}</ref> but also found in deposits in [[Vietnam]] and parts of [[East Africa]]. Padparadscha sapphires are rare; the rarest of all is the totally natural variety, with no sign of artificial treatment.<ref name="Hughes-1997">{{cite book| first=Richard W.| last=Hughes| date=December 1997| title=Ruby & Sapphire| location=Boulder, CO| publisher=RWH Publishing| isbn=978-0-9645097-6-4}}</ref>

The name is derived from the Sanskrit ''padma ranga'' ({{lit|lotus color}}), a color akin to the lotus flower (''[[Nelumbo nucifera]]'').<ref name="Crowningshield-1983">{{cite journal| title=Padparadscha: What's in a Name?| url=http://www.gia.edu/cs/Satellite?c=Page&childpagename=GIA%2FPage%2FGGArticleDetail&pagename=GST%2FDispatcher&cid=1355958490878| last=Crowningshield| first=Robert| journal=[[Gems & Gemology]]| date=Spring 1983| volume=19| issue=1|pages = 30–36|doi = 10.5741/GEMS.19.1.30| bibcode=1983GemG...19...30C | access-date=12 February 2014| archive-url=https://web.archive.org/web/20170628024944/https://www.gia.edu/cs/Satellite?c=Page&childpagename=GIA%2FPage%2FGGArticleDetail&pagename=GST%2FDispatcher&cid=1355958490878| archive-date=28 June 2017| url-status=dead| df=dmy-all}}</ref>

Among the fancy (non-blue) sapphires, natural padparadscha fetch the highest prices. Since 2001, more sapphires of this color have appeared on the market as a result of artificial lattice diffusion of beryllium.<ref name="Emmett-2003">{{cite journal| title=Beryllium diffusion of ruby and sapphire| url=https://www.gia.edu/doc/Summer-2003-Gems-Gemology-Beryllium-Diffusion-Ruby-Sapphire.pdf| first1=John L.| last1=Emmett| first2=Kenneth| last2=Scarratt| first3=Shane F.| last3=McClure| first4=Thomas| last4=Moses| first5=Troy R.| last5=Douthit| first6=Richard| last6=Hughes| first7=Steve| last7=Novak| first8=James E.| last8=Shigley| first9=Wuyi| last9=Wang| first10=Owen| last10=Bordelon| first11=Robert E.| last11=Kane| journal=[[Gems & Gemology]]| date=Spring 2003| volume=39| issue=2| pages=84–135| doi=10.5741/GEMS.39.2.84| access-date=4 November 2019| doi-access=free| bibcode=2003GemG...39...84E| archive-date=1 August 2020| archive-url=https://web.archive.org/web/20200801010424/https://www.gia.edu/doc/Summer-2003-Gems-Gemology-Beryllium-Diffusion-Ruby-Sapphire.pdf| url-status=live}}</ref>

===Star sapphire===
[[File:The Star of Lanka (5784831032).jpg|left|thumb|The 193.39 carat Star of Lanka star sapphire]]
[[File:+68 Komma Sechs - Karat Sternsafir im Rundmogulschliff - Herrenringfassung - 750 Gelbgold - Russische Goldschmiedemeister - Handarbeit um 1990.jpg|thumb|68 carat star sapphire in round mogul cut - men's ring version - 750 yellow gold - Russian goldsmith - handmade around 1990]]
A ''star sapphire'' is a type of sapphire that exhibits a star-like phenomenon known as [[asterism (gemology)|asterism]]; red stones are known as "star rubies". Star sapphires contain intersecting needle-like [[Inclusion (mineral)|inclusions]] following the underlying [[crystal structure]] that causes the appearance of a six-rayed "star"-shaped pattern when viewed with a single overhead light source. The inclusion is often the mineral [[rutile]], a mineral composed primarily of [[titanium dioxide]].<ref name="Emsley-2001">{{cite book |last=Emsley |first=John |title=Nature's Building Blocks: An A-Z Guide to the Elements |year=2001 |isbn=978-0-19-850341-5|pages=451–53 |publisher=[[Oxford University Press]] |location=Oxford}}</ref> The stones are cut ''[[en cabochon]]'', typically with the center of the star near the top of the dome. Occasionally, twelve-rayed stars are found, typically because two different sets of inclusions are found within the same stone, such as a combination of fine needles of rutile with small platelets of [[hematite]]; the first results in a whitish star and the second results in a golden-colored star. During crystallization, the two types of inclusions become preferentially oriented in different directions within the crystal, thereby forming two six-rayed stars that are superimposed upon each other to form a twelve-rayed star.<ref name="DuToit-2014">{{cite web| title=Twelve-Rayed Star Sapphire of Interest| url=http://www.giathai.net/pdf/12rays_purple_star_sapphire.pdf| last=DuToit| first=Garry| publisher=GIA Laboratory, Bangkok| access-date=14 August 2014| archive-date=28 March 2014| archive-url=https://web.archive.org/web/20140328151558/http://www.giathai.net/pdf/12rays_purple_star_sapphire.pdf| url-status=dead}}</ref> Misshapen stars or 12-rayed stars may also form as a result of [[Crystal twinning|twinning]].
The inclusions can alternatively produce a [[Chatoyancy|cat's eye]] effect if the girdle plane of the cabochon is oriented parallel to the crystal's c-axis rather than perpendicular to it. To get a cat's eye, the planes of exsolved inclusions must be extremely uniform and tightly packed. If the dome is oriented in between these two directions, an off-center star will be visible, offset away from the high point of the dome.<ref name="Hughes-2017"/>{{rp|101}}

At 1404.49 carats, [[The Star of Adam]] is the largest known blue star sapphire. The gem was mined in the city of Ratnapura, southern Sri Lanka.<ref name="Sivaramakrishnan-2016">{{cite news | title = World's largest blue star sapphire 'found in Sri Lanka' | url = https://www.bbc.com/news/world-asia-35226276 | first = P | last = Sivaramakrishnan | date = 4 January 2016 | work = BBC News | publisher = [[BBC]] | access-date = 5 January 2016 | archive-date = 5 January 2016 | archive-url = https://web.archive.org/web/20160105031830/http://www.bbc.com/news/world-asia-35226276 | url-status = live }}</ref> The [[Black Star of Queensland]], the second largest star sapphire in the world, weighs 733 [[carat (unit)|carat]]s.<ref name="Kim-2010">{{cite news| url=http://www.latimes.com/news/local/la-me-blacksapphire5-2010jan05,0,872801.story| title=For some, a sapphire has not been their best friend| access-date=5 January 2010| work=[[Los Angeles Times]]| first=Victoria| last=Kim| date=5 January 2010| archive-date=8 January 2010| archive-url=https://web.archive.org/web/20100108084956/http://www.latimes.com/news/local/la-me-blacksapphire5-2010jan05,0,872801.story| url-status=live}}</ref> The [[Star of India (gem)|Star of India]] mined in Sri Lanka and weighing 563.4 carats is thought to be the third-largest star sapphire, and is currently on display at the [[American Museum of Natural History]] in [[New York City]]. The 182-carat [[Star of Bombay]], mined in Sri Lanka and located in the [[National Museum of Natural History]] in [[Washington, D.C.]], is another example of a large blue star sapphire. The value of a star sapphire depends not only on the weight of the stone, but also the body color, visibility, and intensity of the asterism. The color of the stone has more impact on the value than the visibility of the star. Since more transparent stones tend to have better colors, the most expensive star stones are semi-transparent "glass body" stones with vivid colors.<ref name="Hughes-2017"/>{{rp|348–350}}

On 28 July 2021, the world's largest cluster of star sapphires, weighing {{Convert|510|kg|abbr=on}}, was unearthed from Ratnapura, Sri Lanka. This star sapphire cluster was named "[[Serendipity Sapphire]]".<ref>{{Cite web |title=World's largest star sapphire cluster found in backyard |url=https://www.9news.com.au/world/worlds-largest-star-sapphire-cluster-found-in-backyard-in-sri-lanka/1c5b1cc8-fa14-48ac-800c-7516dda154b1 |access-date=28 July 2021 |website=www.9news.com.au |date=28 July 2021 |archive-date=28 July 2021 |archive-url=https://web.archive.org/web/20210728135721/https://www.9news.com.au/world/worlds-largest-star-sapphire-cluster-found-in-backyard-in-sri-lanka/1c5b1cc8-fa14-48ac-800c-7516dda154b1 |url-status=live }}</ref><ref>{{Cite news |last=Salo |first=Jackie |date=27 July 2021 |title=World's largest sapphire cluster worth $100M found in backyard in Sri Lanka |url=https://nypost.com/2021/07/27/worlds-largest-sapphire-cluster-found-in-sri-lankan-yard/ |access-date=28 July 2021 |website=New York Post |language=en-US |archive-date=28 July 2021 |archive-url=https://web.archive.org/web/20210728135726/https://nypost.com/2021/07/27/worlds-largest-sapphire-cluster-found-in-sri-lankan-yard/ |url-status=live }}</ref>

===Color-change sapphire===
A rare variety of natural sapphire, known as color-change sapphire, exhibits different colors in different light. Color change sapphires are blue in outdoor light and purple under [[incandescent]] indoor light, or green to gray-green in daylight and pink to reddish-violet in incandescent light.{{clarification needed|reason=incandescent light used twice to refer to different color states|date=August 2024}} Color-change sapphires come from a variety of locations, including [[Madagascar]], [[Myanmar]], [[Sri Lanka]] and [[Tanzania]]. Two types exist. The first features the [[chromium]] chromophore that creates the red color of ruby, combined with the [[iron]] + [[titanium]] chromophore that produces the blue color in sapphire. A rarer type, which comes from the Mogok area of Myanmar, features a [[vanadium]] chromophore, the same as is present in Verneuil synthetic color-change sapphire.

Virtually all gemstones that show the "alexandrite effect" (color change or '[[Metamerism (color)|metamerism]]') show similar absorption/transmission features in the visible spectrum. This is an absorption band in the yellow (~590&nbsp;nm), along with valleys of transmission in the blue-green and red. Thus the color one sees depends on the spectral composition of the light source. Daylight is relatively balanced in its spectral power distribution (SPD) and since the human eye is most sensitive to green light, the balance is tipped to the green side. However incandescent light (including candle light) is heavily tilted to the red end of the spectrum, thus tipping the balance to red.<ref>{{cite journal| title=Gemstones with alexandrite effect| url=https://www.gia.edu/doc/Gemstones-with-Alexandrite-Effect.pdf| date=Winter 1982| first1=E.| last1=Gübelin| first2=K.| last2=Schmetzer| volume=18| issue=4| journal=Gems & Gemology| pages=197–203| doi=10.5741/GEMS.18.4.197| bibcode=1982GemG...18..197G| access-date=5 November 2019| archive-date=5 November 2019| archive-url=https://web.archive.org/web/20191105010509/https://www.gia.edu/doc/Gemstones-with-Alexandrite-Effect.pdf| url-status=live}}</ref>

Color-change sapphires colored by the Cr + Fe/Ti chromophores generally change from blue or violet-blue to violet or purple. Those colored by the V chromophore can show a more pronounced change, moving from blue-green to purple.

Certain synthetic color-change sapphires have a similar color change to the natural gemstone [[alexandrite]] and they are sometimes marketed as "alexandrium" or "synthetic alexandrite". However, the latter term is a misnomer: synthetic color-change sapphires are, technically, not synthetic alexandrites but rather alexandrite ''simulants''. This is because genuine alexandrite is a variety of [[chrysoberyl]]: not sapphire, but an entirely different mineral from corundum.<ref name="Weldon-2013">{{cite web| title=An Introduction to Synthetic Gem Materials| url=http://www.gia.edu/gem-synthetic| last=Weldon| first=Robert| work=GIA| publisher=Gemological Institute of America Inc.| access-date=14 August 2014| archive-date=12 November 2013| archive-url=https://web.archive.org/web/20131112191736/http://www.gia.edu/gem-synthetic| url-status=live}}</ref>

===Large rubies and sapphires===
Large [[Ruby|rubies]] and sapphires of poor transparency are frequently used with suspect appraisals that vastly overstate their value. This was the case of the "Life and Pride of America Star Sapphire". Circa 1985, Roy Whetstine claimed to have bought the 1905-ct stone for $10 at the Tucson gem show, but a reporter discovered that L.A. Ward of Fallbrook, California, who appraised it at the price of $1200/ct, had appraised another stone of the exact same weight several years before Whetstine claimed to have found it.<ref name="Hughes-2001">{{cite journal| title=Digital Devil: Big Time| url=http://www.ruby-sapphire.com/dd_big_time.htm| last=Hughes| first=Richard W.| journal=[[GK Magazine]]| date=March 2001| volume=3| issue=4| access-date=5 November 2019| archive-date=17 September 2019| archive-url=https://web.archive.org/web/20190917175013/http://www.ruby-sapphire.com/dd_big_time.htm| url-status=dead}}</ref>

Bangkok-based [[Lotus Gemology]] maintains an updated listing of world auction records of ruby, sapphire, and [[spinel]]. As of November 2019, no sapphire has ever sold at auction for more than $17,295,796.<ref>{{cite web | url=https://www.lotusgemology.com/index.php/library/articles/160-ruby-sapphire-spinel-auction-records-under-the-hammer-lotus-gemology | title=Ruby, Sapphire & Spinel Auction Records | access-date=5 November 2019 | author=Hughes, Richard W. | archive-date=5 November 2019 | archive-url=https://web.archive.org/web/20191105042632/https://www.lotusgemology.com/index.php/library/articles/160-ruby-sapphire-spinel-auction-records-under-the-hammer-lotus-gemology | url-status=live }}</ref>

==Cause of color==
[[File:Corundum.png|thumb|Crystal structure of sapphire]]
[[File:Sapphire ring.jpg|thumb|Sapphire ring made {{circa|1940}}]]
[[Rubies]] are [[corundum]] with a dominant red body color. This is generally caused by traces of [[chromium]] (Cr<sup>3+</sup>) substituting for the (Al<sup>3+</sup>) ion in the corundum structure. The color can be modified by both iron and trapped hole color centers.<ref>{{cite web |url=http://www.webexhibits.org/causesofcolor/6AA.html |title=Red Rubies |work=Causes of Color |access-date=14 August 2014 |publisher=[[WebExhibits]] online museum |archive-date=9 May 2020 |archive-url=https://web.archive.org/web/20200509120724/http://www.webexhibits.org/causesofcolor/6AA.html |url-status=live }}</ref>

Unlike localized ("intra-atomic") absorption of light, which causes color for chromium and vanadium impurities, blue color in sapphires comes from intervalence charge transfer, which is the transfer of an electron from one transition-metal ion to another via the [[conduction band|conduction]] or [[valence band]]. The iron can take the form Fe<sup>2+</sup> or Fe<sup>3+</sup>, while titanium generally takes the form Ti<sup>4+</sup>. If Fe<sup>2+</sup> and Ti<sup>4+</sup> ions are substituted for Al<sup>3+</sup>, localized areas of charge imbalance are created. An electron transfer from Fe<sup>2+</sup> and Ti<sup>4+</sup> can cause a change in the [[valence (chemistry)|valence]] state of both. Because of the valence change, there is a specific change in energy for the electron, and [[electromagnetic energy]] is absorbed. The [[wavelength]] of the energy absorbed corresponds to yellow light. When this light is subtracted from incident white light, the complementary color blue results. Sometimes when atomic spacing is different in different directions, there is resulting blue-green [[dichroism]].

Purple sapphires contain trace amounts of [[chromium]] and [[iron]] plus [[titanium]] and come in a variety of shades. Corundum that contains extremely low levels of chromophores is near colorless. Completely colorless corundum generally does not exist in nature. If trace amounts of [[iron]] are present, a very pale yellow to green color may be seen. However, if both titanium and iron impurities are present together, and in the correct [[Valence (chemistry)|valence]] states, the result is a blue color.<ref>{{cite web |url=http://www.webexhibits.org/causesofcolor/8.html |title=Blue Sapphire |work=Causes of Color |access-date=14 August 2014 |publisher=[[WebExhibits]] online museum |archive-date=10 May 2020 |archive-url=https://web.archive.org/web/20200510034749/http://www.webexhibits.org/causesofcolor/8.html |url-status=live }}</ref>

Intervalence charge transfer is a process that produces a strong colored appearance at a low percentage of impurity. While at least 1% chromium must be present in corundum before the deep red ruby color is seen, sapphire blue is apparent with the presence of only 0.01% of titanium and iron.

Colorless sapphires, which are uncommon in nature, were once used as diamond substitutes in jewelry, and are presently used as accent stones.<ref name=GIA/>

The most complete description of the causes of color in corundum extant can be found in Chapter&nbsp;4 of ''Ruby & Sapphire: A Gemologist's Guide'' (chapter authored by John Emmett, Emily Dubinsky and Richard Hughes).<ref name="Hughes-2017"/>{{rp|107–164}}

==Mining==
[[File:1szafir Madagaskar.jpg|thumb|Sapphire from Madagascar]]

Sapphires are mined from [[alluvium|alluvial]] deposits or from primary underground workings. Commercial [[mining]] locations for sapphire and ruby include (but are not limited to) the following countries: [[Afghanistan]], [[Australia]], [[Myanmar]]/[[Burma]], [[Cambodia]], [[China]], [[Colombia]], [[India]], [[Kenya]], [[Laos]], [[Madagascar]], [[Malawi]], [[Nepal]], [[Nigeria]], [[Pakistan]], [[Sri Lanka]], [[Tajikistan]], [[Tanzania]], [[Thailand]], United States, and [[Vietnam]]. Sapphires from different geographic locations may have different appearances or chemical-impurity concentrations, and tend to contain different types of microscopic inclusions. Because of this, sapphires can be divided into three broad categories: classic metamorphic, non-classic metamorphic or magmatic, and classic magmatic.<ref name="GIA-2007">{{cite web| title=Your Ruby and Sapphire Reports| url=http://www.giathai.net/pdf/GIA_Corundum_7499_050307.pdf| publisher=Gemological Institute of America Inc.| work=GIA| date=2007| access-date=17 January 2013| archive-date=15 May 2012| archive-url=https://web.archive.org/web/20120515052118/http://www.giathai.net/pdf/GIA_Corundum_7499_050307.pdf| url-status=dead}}</ref>

Sapphires from certain locations, or of certain categories, may be more commercially appealing than others,<ref name="Gubelin">{{cite web| title=Origin Determination| url=http://www.gubelingemlab.ch/Laboratory-Services/Origin-Determination.php| publisher=Gubelin Gem Labs| access-date=14 August 2014| archive-date=1 February 2014| archive-url=https://web.archive.org/web/20140201212531/http://www.gubelingemlab.ch/Laboratory-Services/Origin-Determination.php| url-status=live}}</ref> particularly classic metamorphic sapphires from Kashmir, Burma, or Sri Lanka that have not been subjected to heat-treatment.<ref name="Michelle-2007">{{cite journal| url=http://www.diamonds.net/Magazine/Article.aspx?ArticleID=20117&RDRIssueID=20| title=The Kashmir Legend| first=Amber| last=Michelle| journal=[[Rapaport Diamond Report]]| date=December 2007| access-date=14 August 2014| archive-date=2 February 2014| archive-url=https://web.archive.org/web/20140202100832/http://www.diamonds.net/Magazine/Article.aspx?ArticleID=20117&RDRIssueID=20| url-status=live}}</ref><ref name="Brooke Showell">{{cite journal| author=Brooke Showell| title=A Fancy for Sapphires| url=http://www.diamonds.net/Magazine/Article.aspx?ArticleID=39646&RDRIssueID=89| journal=Rapaport Diamond Report| access-date=14 August 2014| archive-date=2 February 2014| archive-url=https://web.archive.org/web/20140202101016/http://www.diamonds.net/Magazine/Article.aspx?ArticleID=39646&RDRIssueID=89| url-status=live}}</ref>

The [[Logan sapphire]], the [[Star of India (gem)|Star of India]], [[The Star of Adam]] and the [[Star of Bombay]] originate from Sri Lankan mines. Madagascar is the world leader in sapphire production (as of 2007) specifically its deposits in and around the town of [[Ilakaka]].<ref name="Mindat">{{cite web| url=http://www.mindat.org/loc-27802.html| title=Ilakaka Commune, Ranohira District, Horombe Region, Fianarantsoa Province, Madagascar| work=[[Mindat.org]]| publisher=Hudson Institute of Mineralogy| access-date=14 August 2014| archive-date=11 December 2011| archive-url=https://web.archive.org/web/20111211142515/http://www.mindat.org/loc-27802.html| url-status=live}}</ref> Prior to the opening of the Ilakaka mines, Australia was the largest producer of sapphires (such as in 1987).<ref>{{Cite book| url=https://books.google.com/books?id=auXS_gLKFjUC&pg=PA102| page=102| title=Use with care: managing Australia's natural resources in the twenty-first century| first=Doug| last=Cocks| publisher=University of New South Wales Press| location=Sydney, Australia| year=1992| isbn=978-0-86840-308-3| access-date=6 October 2020| archive-date=23 March 2024| archive-url=https://web.archive.org/web/20240323110143/https://books.google.com/books?id=auXS_gLKFjUC&pg=PA102#v=onepage&q&f=false| url-status=live}}</ref> In 1991 a new source of sapphires was discovered in Andranondambo, southern Madagascar. The exploitation started in 1993, but was practically abandoned just a few years later because of the difficulties in recovering sapphires in their bedrock.<ref>{{cite web | archive-url = https://web.archive.org/web/20040416190825/http://madagascarsapphire.com/andranondambo.htm | archive-date = 16 April 2004 | url = http://madagascarsapphire.com/andranondambo.htm | url-status = dead | title = Andranondambo | date = 2003 | publisher = Madagascar sapphire}}</ref>

In [[North America]], sapphires have been mined mostly from deposits in [[Montana]]: facies along the [[Missouri River]] near [[Helena, Montana]], Dry Cottonwood Creek near [[Deer Lodge, Montana]], and Rock Creek near [[Philipsburg, Montana]]. Fine blue [[Yogo sapphire]]s are found at Yogo Gulch west of [[Lewistown, Montana]].<ref name="Voynick-1985-2" /> A few gem-grade sapphires and rubies have also been found in the area of [[Franklin, NC|Franklin, North Carolina]].<ref>{{cite web|title=Gem Mining in Franklin, NC|url=http://www.franklin-chamber.com/whattodo/gemmining.php|publisher=Franklin, North Carolina Chamber of Commerce|access-date=11 August 2014|archive-date=19 August 2014|archive-url=https://web.archive.org/web/20140819025829/http://www.franklin-chamber.com/whatToDo/gemmining.php|url-status=dead}}</ref>

The sapphire deposits of Kashmir are well known in the gem industry, although their peak production took place in a relatively short period at the end of the nineteenth and early twentieth centuries.<ref name="Hughes-2017"/>{{rp|463–482}} These deposits are located in the [[Paddar Valley]] of the [[Jammu division|Jammu region]] of Jammu and Kashmir in India.<ref name="History of Kashmir Sapphires-2019">{{Cite web|url=https://www.thenaturalsapphirecompany.com/blog/history-kashmir-sapphires|title=History of Kashmir Sapphires|date=13 September 2019|access-date=6 January 2018|archive-date=6 January 2018|archive-url=https://web.archive.org/web/20180106231957/https://www.thenaturalsapphirecompany.com/blog/history-kashmir-sapphires|url-status=live}}</ref> They have a superior vivid blue hue, coupled with a mysterious and almost sleepy quality, described by some gem enthusiasts as ‘blue velvet”. Kashmir-origin contributes meaningfully to the value of a sapphire, and most corundum of Kashmir origin can be readily identified by its characteristic silky appearance and exceptional hue.<ref name="Arem-2017">{{cite web | url = https://www.gemsociety.org/article/sapphire-jewelry-and-gemstone-information/ | title = Sapphire Value, Price, and Jewelry Information | first1 = Dr. Joel | last1 = Arem | first2 = Donald | last2 = Clark | publisher = International Gem Society LLC. | access-date = 12 September 2017 | archive-date = 14 July 2017 | archive-url = https://web.archive.org/web/20170714094431/https://www.gemsociety.org/article/sapphire-jewelry-and-gemstone-information/ | url-status = live }}</ref><ref name="History of Kashmir Sapphires-2019"/> The unique blue appears lustrous under any kind of light, unlike non-Kashmir sapphires which may appear purplish or grayish in comparison.<ref>{{Cite web|url=http://www.sothebys.com/en/auctions/ecatalogue/2015/magnificent-jewels-and-jadeite-hk0590/lot.1860.html|title=The Jewel of Kashmir|archive-url=https://web.archive.org/web/20160323154624/http://www.sothebys.com/en/auctions/ecatalogue/2015/magnificent-jewels-and-jadeite-hk0590/lot.1860.html|archive-date=23 March 2016|url-status=dead}}</ref> Sotheby's has been in the forefront overseeing record-breaking sales of Kashmir sapphires worldwide. In October 2014, Sotheby's Hong Kong achieved consecutive per-carat price records for Kashmir sapphires – first with the 12.00 carat Cartier sapphire ring at US$193,975 per carat, then with a 17.16 carat sapphire at US$236,404, and again in June 2015 when the per-carat auction record was set at US$240,205.<ref name="Sotheby" /> At present, the world record price-per-carat for sapphire at auction is held by a sapphire from Kashmir in a ring, which sold in October 2015 for approximately [[United States dollar|US$]]242,000 per carat ([[Hong Kong dollar|HK$]]52,280,000 in total, including buyer's premium, or more than US$6.74 million).<ref name="Sotheby">{{cite web | url = http://www.sothebys.com/en/auctions/ecatalogue/2015/magnificent-jewels-and-jadeite-hk0590/lot.1860.html | title = 1860: THE JEWEL OF KASHMIR, Exceptional Sapphire and Diamond Ring | work = Magnificent Jewels & Jadeite | publisher = Sotheby's | access-date = 12 September 2017 | archive-date = 23 March 2016 | archive-url = https://web.archive.org/web/20160323154624/http://www.sothebys.com/en/auctions/ecatalogue/2015/magnificent-jewels-and-jadeite-hk0590/lot.1860.html | url-status = live }}</ref>

==Treatments==
Sapphires can be treated by several methods to enhance and improve their clarity and color.<ref name="Hughes-2017"/>{{rp|197–247}} It is common practice to heat natural sapphires to improve or enhance their appearance. This is done by heating the sapphires in furnaces to temperatures between {{convert|800|and|1800|C}} for several hours, or even weeks at a time. Different atmospheres may be used. Upon heating, the stone becomes bluer in color, but loses some of the rutile inclusions (silk). When high temperatures (1400&nbsp;°C+) are used, exsolved rutile silk is dissolved and it becomes clear under magnification. The titanium from the rutile enters solid solution and thus creates with iron the blue color.<ref>{{cite web | url = http://www.gaaj-zenhokyo.co.jp/researchroom/corundum/heat-treatment_01en.html | title = Identification of heated / unheated status on ruby and sapphire | access-date = 21 March 2010 | url-status = dead | archive-url = https://web.archive.org/web/20100309151251/http://www.gaaj-zenhokyo.co.jp/researchroom/corundum/heat-treatment_01en.html | archive-date = 9 March 2010 | date = 2007 | author = Research Laboratory | publisher = Gemmological Association of All Japan Co., Ltd. | df = dmy-all }}</ref> The inclusions in natural stones are easily seen with a [[jeweler's loupe]]. Evidence of sapphire and other gemstones being subjected to heating goes back at least to Roman times.<ref name="Nassau-1984">{{Cite book| last=Nassau| first=Kurt| title=Gemstone Enhancement| year=1984| publisher=Butterworths| page=95| isbn=978-0-408-01447-2}}</ref> Un-heated natural stones are somewhat rare and will often be sold accompanied by a certificate from an independent gemological laboratory attesting to "no evidence of heat treatment".

[[File:Yogo2783 Close crop.JPG|thumb|[[Yogo sapphire]]]]
[[Yogo sapphire]]s do not need heat treating because their [[cornflower blue]] color is attractive out of the ground; they are generally free of [[Inclusion (mineral)|inclusions]], and have high uniform clarity.<ref name="Kane-2003">{{cite journal|last=Kane|first=Robert E.|date=January–February 2003|volume=22|issue=1|title=The Sapphires of Montana – A Rainbow of Colors|journal=Gem Market News|pages=1–8}} Revised January 2004.</ref> When Intergem Limited began marketing the Yogo in the 1980s as the world's only guaranteed untreated sapphire, heat treatment was not commonly disclosed; by the late 1980s, heat treatment became a major issue.<ref name="Voynick-1985-2">{{cite book| last=Voynick| first=Stephen M. |title=Yogo, The Great American Sapphire| publisher=Mountain Press Publishing| year=1985| edition=March 1995 printing, 1987| place=Missoula, MT| isbn=978-0-87842-217-3| pages=151–181}}</ref> At that time, much of all the world's sapphires were being heated to enhance their natural color.<ref name="Voynick-1985">{{harvnb|Voynick|1985|pp=165–181}}</ref> Intergem's marketing of guaranteed untreated Yogos set them against many in the gem industry. This issue appeared as a front-page story in ''[[The Wall Street Journal]]'' on 29 August 1984 in an article by Bill Richards, ''Carats and Schticks: Sapphire Marketer Upsets The Gem Industry''.<ref name="Voynick-1985"/> However, the biggest problem the Yogo mine faced was not competition from heated sapphires, but the fact that the Yogo stones could never produce quantities of sapphire above one carat after faceting. As a result, it has remained a niche product, with a market that largely exists in the US.<ref name="Hughes-2017"/>{{rp| 676–695}}

Lattice ('bulk') diffusion treatments are used to add impurities to the sapphire to enhance color. This process was originally developed and patented by Linde Air division of Union Carbide and involved diffusing titanium into synthetic sapphire to even out the blue color.<ref>{{cite patent
| country	= USA
| number	= US3897529A
| status	= Expired
| title	= Altering the appearance of corundum crystals
| pubdate	= 29 July 1975
| gdate	= 
| fdate	= 
| pridate	= 
| inventor	= 
| invent1	= Ronald R Carr
| invent2	= Stephen D Nisevich
| assign1	= 
| assign2	= 
| class	= 
| url	= https://patents.google.com/patent/US3897529
}} {{Webarchive|url=https://web.archive.org/web/20191105070221/https://patents.google.com/patent/US3897529 |date=5 November 2019 }}</ref> It was later applied to natural sapphire. Today, titanium diffusion often uses a synthetic colorless sapphire base. The color layer created by titanium diffusion is extremely thin (less than 0.5&nbsp;mm). Thus repolishing can and does produce slight to significant loss of color. Chromium diffusion has been attempted, but was abandoned due to the slow diffusion rates of chromium in corundum.

In the year 2000, beryllium diffused "padparadscha" colored sapphires entered the market. Typically [[beryllium]] is diffused into a sapphire under very high heat, just below the melting point of the sapphire. Initially ({{circa|2000}}) orange sapphires were created, although now the process has been advanced and many colors of sapphire are often treated with beryllium. Due to the small size of the beryllium ion, the color penetration is far greater than with titanium diffusion. In some cases, it may penetrate the entire stone. Beryllium-diffused orange sapphires may be difficult to detect, requiring advanced chemical analysis by gemological labs (e.g., Gübelin, [[SSEF]], [[Gemological Institute of America|GIA]], American Gemological Laboratories (AGL), and [[Lotus Gemology]]<ref name="Lotus"/>).

According to United States [[Federal Trade Commission]] guidelines, disclosure is required of any mode of enhancement that has a significant effect on the gem's value.<ref>Chapter I of Title 16 of the Code of Federal Regulations Part 23, Guides for Jewelry and Precious Metals and Pewter Industries</ref>

There are several ways of treating sapphire. Heat-treatment in a reducing or oxidizing atmosphere (but without the use of any other added impurities) is commonly used to improve the color of sapphires, and this process is sometimes known as "heating only" in the gem trade. In contrast, however, heat treatment combined with the deliberate addition of certain specific impurities (e.g. beryllium, titanium, iron, chromium or nickel, which are absorbed into the crystal structure of the sapphire) is also commonly performed, and this process can be known as "diffusion" in the gem trade. However, despite what the terms "heating only" and "diffusion" might suggest, both of these categories of treatment actually involve diffusion processes.<ref name="Nassau-1981">{{cite journal| first=Kurt| last=Nassau| title=Heat Treating Ruby and Sapphire: Technical Aspects| journal=Gems & Gemology| date=Fall 1981| volume=17| issue=3| pages=121–131| doi=10.5741/GEMS.17.3.121| df=dmy-all| doi-access=free| bibcode=1981GemG...17..121N}}</ref>

The most complete description of corundum treatments extant can be found in Chapter 6 of ''Ruby & Sapphire: A Gemologist's Guide'' (chapter authored by John Emmett, Richard Hughes and Troy R. Douthit).<ref name="Hughes-2017"/>{{rp|197–247}}

==Synthetic sapphire== <!--Synthetic sapphire redirects here-->
[[File:Synthetic sapphire 3.jpg|thumb|Synthetic sapphire]]<!-- Deleted image removed: [[File:Labstarsapphirering.JPG|thumb|Synthetic star sapphire]] -->
In 1902, the French chemist [[Auguste Verneuil]] announced a process for producing synthetic [[ruby]] crystals.<ref>{{cite journal | first = M.A. | last = Verneuil | date = September 1904 | title = Mémoire sur la reproduction artificielle du rubis par fusion | trans-title = Memoire on the artificial reproduction of rubies by fusion | journal = [[Annales de Chimie et de Physique]] | volume = 3 | issue = 20}}</ref> In the flame-fusion ([[Verneuil process]]), fine [[alumina]] powder is added to an [[oxyhydrogen flame]], and this is directed downward against a ceramic pedestal.<ref>Heaton, Neal; ''The production and identification of artificial precious stones'' in {{cite book
|title = Annual Report of the Board of Regents of the Smithsonian Institution, 1911
|publisher = Government Printing Office
|year = 1912
|location = USA
|page = 217
|url = https://books.google.com/books?id=hZIKAAAAIAAJ&pg=PA227
|access-date = 6 October 2020
|archive-date = 23 March 2024
|archive-url = https://web.archive.org/web/20240323110127/https://books.google.com/books?id=hZIKAAAAIAAJ&pg=PA227#v=onepage&q&f=false
|url-status = live
}}</ref> Following the successful synthesis of ruby, Verneuil focused his efforts on sapphire. Synthesis of blue sapphire came in 1909, after chemical analyses of sapphire suggested to Verneuil that iron and titanium were the cause of the blue color. Verneuil patented the process of producing synthetic blue sapphire in 1911.<ref>{{cite patent
| country	= USA
| number	= 988,230
| status	= 
| title	= Process of producing synthetic sapphires
| pubdate	= 28 March 1911
| gdate	= 
| fdate	= 
| pridate	= 
| inventor	= August Verneuil
| invent1	= 
| invent2	= 
| assign1	= 
| assign2	= 
| class	= 
| url	= https://patents.google.com/patent/US988230
}} {{Webarchive|url=https://web.archive.org/web/20191105065422/https://patents.google.com/patent/US988230 |date=5 November 2019 }}</ref><ref name="Hughes-2017"/>{{rp|254–255}}

The key to the process is that the alumina powder does not melt as it falls through the flame. Instead it forms a [[Sintering|sinter]] cone on the pedestal. When the tip of that cone reaches the hottest part of the flame, the tip melts. Thus the crystal growth is started from a tiny point, ensuring minimal strain.

Next, more oxygen is added to the flame, causing it to burn slightly hotter. This expands the growing crystal laterally. At the same time, the pedestal is lowered at the same rate that the crystal grows vertically. The alumina in the flame is slowly deposited, creating a teardrop shaped "[[boule (crystal)|boule]]" of sapphire material. This step is continued until the desired size is reached, the flame is shut off and the crystal cools. The now elongated crystal contains a lot of strain due to the high thermal gradient between the flame and surrounding air. To release this strain, the now finger-shaped crystal will be tapped with a [[chisel]] to split it into two halves.<ref name="Hughes-2017"/>{{rp|249–309}}

Due to the vertical layered growth of the crystal and the curved upper growth surface (which starts from a drop), the crystals will display curved growth lines following the top surface of the boule. This is in contrast to natural corundum crystals, which feature angular growth lines expanding from a single point and following the planar crystal faces.<ref>{{cite web | url = https://www.lotusgemology.com/index.php/library/articles/273-verneuil-synthetic-corundum-id-dangerous-curves-lotus-gemology | title = Verneuil Synthetic Corundum ID • Dangerous Curves | work = LotusGemology.com | publisher = Lotus Gemology | access-date = 5 November 2019 | archive-date = 5 November 2019 | archive-url = https://web.archive.org/web/20191105024741/https://www.lotusgemology.com/index.php/library/articles/273-verneuil-synthetic-corundum-id-dangerous-curves-lotus-gemology | url-status = dead }}</ref><!-- Deleted image removed: [[File:Distribution of curved growth lines and gas bubbles in Verneuil synthetic corundum.jpg|thumb|right| Distribution of curved growth lines and gas bubbles in Verneuil synthetic corundum.]] -->

===Dopants===
Chemical [[dopant]]s can be added to create artificial versions of the ruby, and all the other natural colors of sapphire, and in addition, other colors never seen in [[geological]] samples. Artificial sapphire material is identical to natural sapphire, except it can be made without the flaws that are found in natural stones. The disadvantage of the Verneuil process is that the grown crystals have high internal strains. Many methods of manufacturing sapphire today are variations of the [[Czochralski process]], which was invented in 1916 by Polish chemist [[Jan Czochralski]].<ref>{{cite web | url = http://www.articleworld.org/index.php/Czochralski_process | title = Czochralski process | work = articleworld.org | publisher = ArticleWorld | access-date = 18 June 2012 | archive-date = 28 September 2011 | archive-url = https://web.archive.org/web/20110928212136/http://www.articleworld.org/index.php/Czochralski_process | url-status = live }}</ref> In this process, a tiny sapphire seed crystal is dipped into a crucible made of the precious metal [[iridium]] or [[molybdenum]],<ref>{{cite journal|doi=10.1111/j.1151-2916.1962.tb11037.x|title=Application of Czochralski Crystal-Pulling Technique to High-Melting Oxides|year=1962|last1=Nassau|first1=K.|last2=Broyer|first2=A. M.|journal=Journal of the American Ceramic Society|volume=45|issue=10|page=474}}</ref> containing molten alumina, and then slowly withdrawn upward at a rate of 1 to 100&nbsp;mm per hour. The alumina crystallizes on the end, creating long carrot-shaped boules of large size up to 200&nbsp;kg in mass.<ref>{{cite news | url = http://www.ledinside.com/news/2009/4/Rubicon_Technology_Grows_Super_boule_of_200kg_Weight_20090421 | title = Rubicon Technology Grows 200kg "Super Boule" | work = LED Inside | date = 21 April 2009 | first = Judy | last = Huang | publisher = TrendForce Corp. | access-date = 23 September 2013 | archive-date = 10 September 2013 | archive-url = https://web.archive.org/web/20130910104301/http://www.ledinside.com/news/2009/4/Rubicon_Technology_Grows_Super_boule_of_200kg_Weight_20090421 | url-status = live }}</ref> One popular variant of the Czochralski method is the [[Kyropoulos method]] which has the advantage of using all of the feedstock material such as aluminum oxide to create sapphire and crucibles do not have to be replaced. This is one of the main production methods for synthetic sapphire. However the original Czochralski method can also be used. <ref>{{cite book | url=https://books.google.com/books?id=ZqTkCF6Ra9kC&dq=sapphire+crystal+production&pg=PA312 | title=Bulk Crystal Growth of Electronic, Optical and Optoelectronic Materials | isbn=978-0-470-01207-9 | last1=Capper | first1=Peter | date=31 October 2005 | publisher=John Wiley & Sons }}</ref><ref>{{cite book | url=https://books.google.com/books?id=IchDpFiLrGQC&q=Heat+Exchange+Method&pg=PA470 | title=Sapphire: Material, Manufacturing, Applications | isbn=978-0-387-85695-7 | last1=Dobrovinskaya | first1=Elena R. | last2=Lytvynov | first2=Leonid A. | last3=Pishchik | first3=Valerian | date=21 April 2009 | publisher=Springer }}</ref>

===Other growth methods===
Synthetic sapphire is also produced industrially from agglomerated aluminum oxide, sintered and fused (such as by [[hot isostatic pressing]]) in an inert atmosphere, yielding a transparent but slightly [[porous]] [[polycrystalline]] product.<ref>{{Cite web|url=https://www.gemsociety.org/article/lab-grown-sapphires/|title=What are Lab-Grown Sapphires?|website=International Gem Society|language=en|access-date=25 October 2019|archive-date=25 October 2019|archive-url=https://web.archive.org/web/20191025184315/https://www.gemsociety.org/article/lab-grown-sapphires/|url-status=live}}</ref> Another popular method is the Heat Exchanger Method (HEM), in which aluminum oxide is placed in a molybdenum crucible and heated until melting at 2200°C. It allows for very large crystals over 30 cm wide to be produced. The process takes place in a vacuum. A sapphire seed crystal sits at the bottom of the crucible and is kept from melting by heat exchange (cooling) with helium gas or liquid helium which is shielded from the vacuum. The furnace is kept at a temperature just above melting, but the heat exchanger is at a temperature just below melting. Then the heat exchanger temperature is lowered to start crystalization, and then the aluminum oxide is cooled over a period of at least 72 hours to 17 days to crystalize it into sapphire. The crucibles are single use, the process is similar to the [[Bridgman–Stockbarger method|Bridgman technique]] and the Stöber methods for crystal growth,<ref>{{cite book | url=https://books.google.com/books?id=ZqTkCF6Ra9kC&dq=heat+exchange+method+crystal+growth&pg=PA312 | title=Bulk Crystal Growth of Electronic, Optical and Optoelectronic Materials | isbn=978-0-470-01207-9 | last1=Capper | first1=Peter | date=31 October 2005 | publisher=John Wiley & Sons }}</ref><ref>{{cite book | url=https://books.google.com/books?id=1hZ0AwAAQBAJ&dq=heat+exchange+method+crystal+growth&pg=PA30 | title=Handbook of Crystal Growth: Fundamentals | isbn=978-0-444-59376-4 | last1=Nishinaga | first1=Tatau | date=4 November 2014 | publisher=Elsevier }}</ref> and was used for iPhone screens.<ref>{{cite web | url=https://www.wsj.com/articles/inside-apples-broken-sapphire-factory-1416436043 | title=Inside Apple's Broken Sapphire Factory | work=Wall Street Journal | date=19 November 2014 | last1=Wakabayashi | first1=Daisuke }}</ref><ref>{{cite web | url=https://m.youtube.com/watch?v=vsCER0uwiWI | title=Sapphire Screen: The Making of a Scratch-Proof Smartphone Display &#124; Pocketnow | website=[[YouTube]] | date=3 April 2013 }}</ref><ref>{{cite book | url=https://books.google.com/books?id=IchDpFiLrGQC&q=Heat+Exchange+Method&pg=PA470 | title=Sapphire: Material, Manufacturing, Applications | isbn=978-0-387-85695-7 | last1=Dobrovinskaya | first1=Elena R. | last2=Lytvynov | first2=Leonid A. | last3=Pishchik | first3=Valerian | date=21 April 2009 | publisher=Springer }}</ref><ref>{{cite journal |last1=Khattak |first1=Chandra P. |last2=Schmid |first2=Frederick |title=Growth of the world's largest sapphire crystals |journal=Journal of Crystal Growth |date=May 2001 |volume=225 |issue=2–4 |pages=572–579 |doi=10.1016/S0022-0248(01)00955-1 |bibcode=2001JCrGr.225..572K }}</ref> The crystal grows upward from the bottom of the crucible.<ref>{{cite book | url=https://books.google.com/books?id=1hZ0AwAAQBAJ&dq=heat+exchange+method+crystal+growth&pg=PA30 | title=Handbook of Crystal Growth: Fundamentals | isbn=978-0-444-59376-4 | last1=Nishinaga | first1=Tatau | date=4 November 2014 | publisher=Elsevier }}</ref> Another method is the Edge-defined Film-fed Growth (EFG) method, very similar to the Czochralski method but the material passes through a die before cooling, which shapes the crystal. The crystal does not rotate.<ref>{{cite book | url=https://books.google.com/books?id=IchDpFiLrGQC&q=Heat+Exchange+Method&pg=PA470 | title=Sapphire: Material, Manufacturing, Applications | isbn=978-0-387-85695-7 | last1=Dobrovinskaya | first1=Elena R. | last2=Lytvynov | first2=Leonid A. | last3=Pishchik | first3=Valerian | date=21 April 2009 | publisher=Springer }}</ref> Chemical Vapor Deposition (CVD), gradient furnace<ref>{{cite journal |last1=Schmid |first1=F. |last2=Viechnicki |first2=D. |title=Growth of Sapphire Disks from the Melt by a Gradient Furnace Technique |journal=Journal of the American Ceramic Society |date=September 1970 |volume=53 |issue=9 |pages=528–529 |doi=10.1111/J.1151-2916.1970.TB16009.X }}</ref> or vertical bridgman processes can be used for sapphire crystal growth.<ref>{{cite journal |last1=Khattak |first1=Chandra P. |last2=Schmid |first2=Frederick |title=Growth of the world's largest sapphire crystals |journal=Journal of Crystal Growth |date=May 2001 |volume=225 |issue=2–4 |pages=572–579 |doi=10.1016/S0022-0248(01)00955-1 |bibcode=2001JCrGr.225..572K }}</ref>

In 2003, the world's production of synthetic sapphire was 250 tons (1.25 billion carats), mostly by the United States and Russia.<ref name="Scheel-2003">{{Cite book|author1=Scheel, Hans Jr̲g|author2=Fukuda, Tsuguo|title=Crystal growth technology|year=2003|publisher=J. Wiley|location=Chichester, West Sussex|isbn=978-0-471-49059-3|url=http://media.wiley.com/product_data/excerpt/98/04714905/0471490598.pdf|access-date=24 May 2006|archive-date=5 September 2012|archive-url=https://web.archive.org/web/20120905093214/http://media.wiley.com/product_data/excerpt/98/04714905/0471490598.pdf|url-status=live}}</ref><ref>{{cite book|url=https://books.google.com/books?id=IchDpFiLrGQC&pg=PA3|page=3|title=Sapphire: Materials, Manufacturing, Applications|author1=Elena R. Dobrovinskaya|author2=Leonid A. Lytvynov|author3=Valerian Pishchik|publisher=Springer|year=2009|isbn=978-0-387-85694-0|access-date=6 October 2020|archive-date=23 March 2024|archive-url=https://web.archive.org/web/20240323110143/https://books.google.com/books?id=IchDpFiLrGQC&pg=PA3#v=onepage&q&f=false|url-status=live}}</ref> The availability of cheap synthetic sapphire unlocked many industrial uses for this unique material.

===Applications===
====Equipment windows====
[[File:cermax.jpg|thumb|Cermax [[xenon arc lamp]] with synthetic sapphire output window]]
[[File:Citizen Eco-Drive Titanium Sapphire.jpg|thumb|[[Wristwatch]] with synthetic sapphire watch crystal]]

Synthetic sapphire—also referred to as ''sapphire glass''—is commonly used for small windows, because it is both highly transparent to wavelengths of light between 150&nbsp;nm ([[Ultraviolet|UV]]) and 5500&nbsp;nm ([[Infrared|IR]]) (the visible [[spectrum]] extends about 380&nbsp;nm to 750&nbsp;nm<ref>{{cite book|title = Biology: Concepts and Applications|author = Cecie Starr|publisher = Thomson Brooks/Cole|year = 2005|isbn = 978-0-534-46226-0|url = https://books.google.com/books?id=RtSpGV_Pl_0C&pg=PA94|page=94}}</ref>), and extraordinarily scratch-resistant.<ref>{{cite press release |url=http://www.corning.com/news_center/features/gorillaglasssuccess.aspx | url-status = dead | title = Corning® Gorilla® Glass Now Found On More Than 1.5 Billion Devices: Continuing innovation to fuel future versions, Sapphire not seen as major threat | date = May 2013 | location = Corning, N.Y. |publisher=Corning Incorporated | archive-url = https://web.archive.org/web/20130607071047/http://www.corning.com/news_center/features/gorillaglasssuccess.aspx | archive-date = 7 June 2013}}</ref><ref>{{cite web | url = http://www.cultofmac.com/267068/everything-wanted-know-sapphire-glass-afraid-ask-qa/ | title = Everything You Wanted To Know About Sapphire Glass, But Were Afraid To Ask [Q&A] | first = Luke | last = Dormehl | date = 19 February 2014 | work = Cult of Mac | access-date = 7 October 2014 | archive-date = 11 October 2014 | archive-url = https://web.archive.org/web/20141011070950/http://www.cultofmac.com/267068/everything-wanted-know-sapphire-glass-afraid-ask-qa/ | url-status = live }}</ref>

The key benefits of sapphire windows are:

* Very wide optical transmission band from [[UV]] to [[near infrared]] (0.15–5.5&nbsp;μm)
* Significantly stronger than other optical materials or standard glass windows
* Highly resistant to scratching and abrasion (9 on the [[Mohs scale of mineral hardness]] scale, the third-hardest natural substance next to [[moissanite]] and diamonds)<ref name="Arem-2017" />
* Extremely high melting temperature (2030&nbsp;°C)

[[File:Sapphire boule, Kyropoulos method.jpg|thumb|upright|Single-crystal sapphire boule grown by the [[Kyropoulos method]].<ref>{{cite web | url=http://functmaterials.org.ua/contents/32-1/0 | title="Functional materials", Vol.32, No.1, 2025. &#124; Journal "Functional Materials" }}</ref><ref>{{cite journal |last1=Fang |first1=H.S. |last2=Jin |first2=Z.L. |last3=Zhang |first3=M.J. |last4=Zhang |first4=Z. |last5=Zhao |first5=C.J. |title=Role of internal radiation at the different growth stages of sapphire by Kyropoulos method |journal=International Journal of Heat and Mass Transfer |date=December 2013 |volume=67 |pages=967–973 |doi=10.1016/j.ijheatmasstransfer.2013.08.074 |bibcode=2013IJHMT..67..967F }}</ref> Approximately {{convert|200|mm|in|0}} in diameter, weighing approximately {{cvt|30|kg}}. (A second boule is visible in the background.)]]
Some sapphire-glass windows are made from pure sapphire boules that have been grown in a specific crystal orientation, typically along the optical axis, the ''c''&nbsp;axis, for minimum [[birefringence]] for the application.<ref>{{cite book |last1=Dobrovinskaya |first1=Elena R. |last2=Lytvynov |first2=Leonid A. |last3=Pishchik |first3=Valerian |title=Sapphire |chapter=Properties of Sapphire |series=Micro- and Opto-Electronic Materials, Structures, and Systems |date=2009 |pages=55–176 |doi=10.1007/978-0-387-85695-7_2 |isbn=978-0-387-85694-0 |url=https://www.springer.com/cda/content/document/cda_downloaddocument/9780387856940-c1.pdf |access-date=11 September 2017 |archive-date=15 February 2017 |archive-url=https://web.archive.org/web/20170215163235/http://www.springer.com/cda/content/document/cda_downloaddocument/9780387856940-c1.pdf? |url-status=live }}</ref><ref>{{cite web |title=Crystals – Introduction |url=http://www.quartzpage.de/crs_intro.html |website=The Quartz Page |archive-url=https://web.archive.org/web/20071010190156/http://www.quartzpage.de/crs_intro.html |archive-date=10 October 2007}}</ref>

The boules are sliced up into the desired window thickness and finally polished to the desired surface finish. Sapphire optical windows can be polished to a wide range of surface finishes due to its crystal structure and its hardness. The surface finishes of optical windows are normally called out by the scratch-dig specifications in accordance with the globally adopted MIL-O-13830 specification.{{clarify|date=October 2017}}

Sapphire windows are used in both high-pressure and vacuum chambers for [[spectroscopy]], crystals for [[watch]]es, and windows in grocery-store [[barcode scanner]]s, since the material's exceptional hardness and toughness makes it very resistant to scratching.<ref name="Scheel-2003"/>

In 2014 [[Apple Inc.|Apple]] consumed "one-fourth of the world's supply of sapphire to cover the [[iPhone]]'s camera lens and fingerprint reader".<ref>{{Cite news |last=Wakabayashi |first=Daisuke |date=19 November 2014 |title=Inside Apple's Broken Sapphire Factory |language=en-US |work=[[The Wall Street Journal]] |url=https://online.wsj.com/articles/inside-apples-broken-sapphire-factory-1416436043 |access-date=14 December 2021 |archive-date=4 December 2014 |archive-url=https://web.archive.org/web/20141204152117/http://online.wsj.com/articles/inside-apples-broken-sapphire-factory-1416436043 |url-status=live }}</ref>

Several attempts have been made to make sapphire screens for smartphones viable. Apple contracted GT Advanced Technologies, Inc. to manufacture sapphire screens for iPhones, but the venture failed, causing the bankruptcy of GTAT.<ref>{{Cite web |date=14 November 2014 |title=The desperate struggle at the heart of the brutal Apple supply chain |url=http://www.theguardian.com/technology/2014/nov/14/sapphire-gt-advanced--brutal-apple-supply-chain |access-date=14 December 2021 |website=the Guardian |language=en |archive-date=14 December 2021 |archive-url=https://web.archive.org/web/20211214165033/https://www.theguardian.com/technology/2014/nov/14/sapphire-gt-advanced--brutal-apple-supply-chain |url-status=live }}</ref> The [[Kyocera]] Brigadier was the first production smartphone with a sapphire screen.<ref>{{Cite web |last=T. |first=Florin |title=Meet the world's first smartphone with Sapphire Shield display (no, it's not an iPhone) |url=https://www.phonearena.com/news/Meet-the-worlds-first-smartphone-with-Sapphire-Shield-display-no-its-not-an-iPhone_id58847 |access-date=14 December 2021 |website=Phone Arena |date=31 July 2014 |language=en-US |archive-date=14 December 2021 |archive-url=https://web.archive.org/web/20211214165031/https://www.phonearena.com/news/Meet-the-worlds-first-smartphone-with-Sapphire-Shield-display-no-its-not-an-iPhone_id58847 |url-status=live }}</ref>

Sapphire is used for end windows on some high-powered laser tubes, as its wide-band transparency and thermal conductivity allow it to handle very high power densities in the infrared and UV spectrum without degrading due to heating.

One type of [[xenon arc lamp]]{{snd}}originally called the "Cermax" and now known generically as the "ceramic-body xenon lamp"{{snd}}uses sapphire crystal output windows that tolerate higher thermal loads and consequently can provide higher output powers than conventional Xe lamps with pure [[silica]] windows.<ref>{{cite web |url=http://www.perkinelmer.com/cmsresources/Images/44-6529bro_cermaxproductsandspecifications.pdf |title=Cermax® Products and Specifications |publisher=PerkinElmer Optoelectronics |location=Fremont, California, USA |access-date=12 September 2017 |archive-date=12 September 2017 |archive-url=https://web.archive.org/web/20170912233638/http://www.perkinelmer.com/cmsresources/Images/44-6529bro_cermaxproductsandspecifications.pdf |url-status=live }}</ref><ref>{{cite web | url = http://www.excelitas.com/Downloads/Cermax_Eng_Guide.pdf | title = Cermax® Xenon Lamp Engineering Guide | publisher = Excelitas Technologies | access-date = 12 September 2017 | archive-date = 30 August 2014 | archive-url = https://web.archive.org/web/20140830161825/http://excelitas.com/Downloads/Cermax_Eng_Guide.pdf | url-status = live }}</ref>

Sapphire window was used for the [[F-35 Lightning 2]] Electro Optical Targeting System window, due to its high strength.<ref>{{Cite web |url=https://www.lockheedmartin.com/en-us/products/f-35-lightning-ii-eots.html |title=F-35 Electro Optical Targeting System (EOTS) |access-date=12 May 2024 |archive-date=13 May 2024 |archive-url=https://web.archive.org/web/20240513161553/https://www.lockheedmartin.com/en-us/products/f-35-lightning-ii-eots.html |url-status=live }}</ref>
[[File:F-35 EOTS at ILA-2022.jpg | thumb|220x124px | right]]

Along with [[Zirconium dioxide|zirconia]] and [[aluminum oxynitride]], synthetic sapphire is used for shatter-resistant windows in armored vehicles and various military [[body armor]] suits, in association with composites.{{citation needed|date=February 2025}}

====As substrate for semiconducting circuits====
{{main|Silicon on sapphire}}
{{More citations needed section|date=March 2021}}

Thin sapphire wafers were the first successful use of an insulating [[substrate (semiconductor)|substrate]] upon which to deposit silicon to make the [[integrated circuit]]s known as [[silicon on sapphire]] or "SOS"; now other substrates can also be used for the class of circuits known more generally as [[silicon on insulator]]. Besides its excellent electrical insulating properties, sapphire has high [[thermal conductivity]]. [[CMOS]] chips on sapphire are especially useful for high-power radio-frequency (RF) applications such as those found in [[cellular telephones]], [[police radio|public-safety band]] radios, and [[satellite communication]] systems. "SOS" also allows for the monolithic integration of both [[digital electronics|digital]] and [[analog electronics|analog]] circuitry all on one IC chip, and the construction of extremely low power circuits.

In one process, after single crystal sapphire boules are grown, they are core-drilled into cylindrical rods, and wafers are then sliced from these cores.{{citation needed|date=October 2014}}

Wafers of single-crystal sapphire are also used in the [[semiconductor]] industry as [[substrate (semiconductor)|substrates]] for the growth of devices based on [[gallium nitride]] (GaN). The use of sapphire significantly reduces the cost, because it has about one-seventh the cost of [[germanium]]. Gallium nitride on sapphire is commonly used in blue [[light-emitting diodes]] (LEDs).<ref>"Gallium nitride collector grid solar cell" (2002) {{US patent|6447938}}</ref>

====In lasers====
[[File:ODIN Ti-Sapphire laser in operation.jpg|thumb|Ti-Sapphire laser in operation at [[Czech Academy of Sciences|CAS]], Prague]]

The first [[laser]] was made in 1960 by [[Theodore Maiman]] with a rod of [[synthetic ruby]]. [[Ti-sapphire laser|Titanium-sapphire laser]]s are popular due to their relatively rare capacity to be tuned to various wavelengths in the red and near-[[infrared]] region of the [[electromagnetic spectrum]]. They can also be easily [[mode-locking|mode-locked]]. In these lasers a synthetically produced sapphire [[crystal]] with chromium or [[titanium]] impurities is irradiated with intense light from a special lamp, or another laser, to create [[stimulated emission]].

====In endoprostheses====
Monocrystalline sapphire is fairly biocompatible and the exceptionally low wear of sapphire–metal pairs has led to the introduction (in Ukraine) of sapphire monocrystals for hip joint [[prosthesis|endoprostheses]].<ref name="Mamalis-2006">{{cite journal|last1=Mamalis|first1=AG|last2=Ramsden|first2=JJ|last3=Grabchenko|first3=AI|last4=Lytvynov|first4=LA|last5=Filipenko|first5=VA|last6=Lavrynenko|first6=SN|title=A novel concept for the manufacture of individual sapphire-metallic hip joint endoprostheses|journal=Journal of Biological Physics and Chemistry|date=2006|volume=6|issue=3|pages=113–117|doi=10.4024/30601.jbpc.06.03|doi-access=free|hdl=1826/2527|hdl-access=free}}</ref>

==Historical and cultural references==
* Etymologically, the English word "sapphire" derives from French ''{{Lang|fr|saphir}}'', from Latin ''{{Lang|la|sapphirus}}'', ''sappirus'' from Greek σαπφειρος (''sappheiros'') from Hebrew {{Lang|he|סַפִּיר}} ({{Transliteration|he|sapir}}), a term that probably originally referred to [[lapis lazuli]], as sapphires were only discovered in Roman times. The term is believed to derive from the root סָפַר (''sāp̄ar''), meaning "to score with a mark," presumably because gemstones can be used to scratch stone surfaces due to their high [[hardness]].<ref>{{Cite web|url=https://www.blueletterbible.org/net/gen/1/1/s_1001|title=H5601 - sapîr - Strong's Hebrew Lexicon (net)|website=Blue Letter Bible|access-date=2 March 2023|archive-date=2 March 2023|archive-url=https://web.archive.org/web/20230302095026/https://www.blueletterbible.org/net/gen/1/1/s_1001|url-status=live}}</ref><ref>{{Cite web|url=https://jewishencyclopedia.com/articles/13190-sapphire|title=SAPPHIRE - JewishEncyclopedia.com|website=jewishencyclopedia.com|access-date=2 March 2023|archive-date=2 March 2023|archive-url=https://web.archive.org/web/20230302094736/https://jewishencyclopedia.com/articles/13190-sapphire|url-status=live}}</ref><ref name="Harper">{{OEtymD|sapphire}}</ref>
* A traditional [[Hinduism|Hindu]] belief holds that the sapphire causes the planet Saturn ([[Shani]]) to be favorable to the wearer.<ref>The Curious Lore of Precious Stones: Being a Description of Their Sentiments and Folk Lore, Superstitions, Symbolism, Mysticism, Use in Medicine, Protection, Prevention, Religion, and Divination. Crystal Gazing, Birthstones, Lucky Stones, and Talismans, Astral, Zodiacal, and Planetary by George Frederick Kunz, 1913, p. 334</ref>
* The Greek term for sapphire quite likely was instead used to refer to [[lapis lazuli]].<ref name="Harper"/>
* During the [[Medieval Ages]], European [[lapidaries]] came to refer to blue corundum crystal by "sapphire", a derivative of the [[Latin]] word for blue: {{Lang|la|sapphirus}}.<ref>{{cite web |title=History and origin of the Sapphire |url=http://www.gemstoneeducation.com/Sapphire.htm |access-date=3 November 2016 |archive-url=https://web.archive.org/web/20160304042107/http://www.gemstoneeducation.com/Sapphire.htm |archive-date=4 March 2016}}</ref>
* The sapphire is the traditional gift for a 45th [[Wedding anniversary#Traditional anniversary gifts|wedding anniversary]].<ref>{{cite web|title=Anniversary Gifts by Year|url=http://www.happy-anniversary.com/year-of-marriage/|access-date=11 August 2014|archive-date=10 August 2014|archive-url=https://web.archive.org/web/20140810064118/http://www.happy-anniversary.com/year-of-marriage/|url-status=live}}</ref>
* A [[sapphire jubilee]] occurs after 65 years. 2017 marked the sapphire jubilee of the accession of Queen [[Elizabeth II]] to the throne.<ref name="BBC-2017">{{cite news |date=6 February 2017 |title=Queen's Sapphire Jubilee: Gun salutes mark 65 years on the throne |url=https://www.bbc.co.uk/news/uk-38872538 |url-status=live |archive-url=https://web.archive.org/web/20180925054630/https://www.bbc.co.uk/news/uk-38872538 |archive-date=25 September 2018 |access-date=21 June 2018 |publisher=BBC News}}</ref>
* The sapphire is the [[birthstone]] of September.
* An Italian superstition holds that sapphires are [[amulet]]s against eye problems, and [[Melancholia|melancholy]].<ref>''Encyclopedia of Superstitions, Folklore, and the Occult Sciences of the World'', Volume 2 edited by Cora Linn Daniels, C. M. Stevans p.&nbsp;747</ref> [[Mary, Queen of Scots]], owned a medicinal sapphire worn as a pendant to rub sore eyes.<ref>[[Joseph Robertson (historian)|Joseph Robertson]], ''Inventaires'' (Edinburgh, 1863), pp. 81, 101.</ref>
* Pope [[Innocent III]] decreed that rings of bishops should be made of pure gold, set with an unengraved sapphire, as possessing the virtues and qualities essential to its dignified position as a seal of secrets, for there be many things "that a priest conceals from the senses of the vulgar and less intelligent; which he keeps locked up as it were under seal."<ref>The Book of Talismans, Amulets and Zodiacal Gems, by William Thomas and Kate Pavitt, [1922], p.154 at sacred-texts.com, http://www.sacred-texts.com/sym/bot/bot17.htm {{Webarchive|url=https://web.archive.org/web/20180827133657/http://www.sacred-texts.com/sym/bot/bot17.htm |date=27 August 2018 }}, accessed 10 September 2018</ref>
*The sapphire is the official [[Symbols of Queensland|state gem]] of [[Queensland]] since August 1985.<ref>{{Cite web|last=|first=|title=State gem {{!}} State flags, emblems, and icons|url=https://www.qld.gov.au/about/how-government-works/flags-emblems-icons/state-gem|access-date=27 October 2021|website=www.qld.gov.au|language=en|archive-date=27 October 2021|archive-url=https://web.archive.org/web/20211027032933/https://www.qld.gov.au/about/how-government-works/flags-emblems-icons/state-gem|url-status=live}}</ref>

==Notable sapphires==
<!-- This list will never be complete, but it is sparse. Please add notable sapphires, with citations. -->

{| class="wikitable sortable plainrowheaders"
|+Overview of notable sapphires
|-
!scope="col" | Sapphire
!scope="col" | Origin
!scope="col" data-sort-type="number" | Size
!scope="col" | Cut
!scope="col" | Color
!scope="col" | Location
|-
!scope="row"| [[Bismarck Sapphire Necklace|Bismarck Sapphire]]<ref>{{cite web | url = http://geogallery.si.edu/index.php/10002691/bismarck-sapphire-necklace | title = Bismarck Sapphire Necklace | work = Smithsonian National Museum of Natural History | publisher = [[Smithsonian Institution]] | access-date = 7 August 2017 | archive-date = 8 August 2017 | archive-url = https://web.archive.org/web/20170808033841/http://geogallery.si.edu/index.php/10002691/bismarck-sapphire-necklace | url-status = live }}</ref>
| [[Myanmar]]
| 98.56 carats
| Table
| Blue
| [[National Museum of Natural History]], Washington, D.C.
|-
!scope="row"| [[Black Star of Queensland]]<ref name="Kim-2010"/>
| Australia, 1938
| 733 carats
| Star
| Black
| Anonymous owner
|-
!scope="row"| Blue Belle of Asia<ref>{{cite web |title=10 jewels that made history |url=https://www.christies.com/features/10-jewels-that-created-auction-history-and-changed-the-market-9549-3.aspx?sc_lang=en&lid=1 |website=Christies |access-date=22 December 2019 |archive-date=16 March 2020 |archive-url=https://web.archive.org/web/20200316045906/https://www.christies.com/features/10-jewels-that-created-auction-history-and-changed-the-market-9549-3.aspx?sc_lang=en&lid=1 |url-status=live }}</ref>
| Sri Lanka
| 392.52 carats
| Cushion
| Blue
| Anonymous owner
|-
!scope="row"| [[Logan Sapphire]]<ref>{{cite web |title=Logan Sapphire [G3703] |publisher=Smithsonian National Museum of Natural History |url=http://geogallery.si.edu/index.php/10002687/logan-sapphire |access-date=20 July 2016 |archive-date=15 August 2016 |archive-url=https://web.archive.org/web/20160815200533/http://geogallery.si.edu/index.php/10002687/logan-sapphire |url-status=live }}</ref>
| Sri Lanka
| 422.99 carats
| Cushion
| Blue
| National Museum of Natural History, Washington, D.C.
|-
!scope="row"| [[Queen Marie of Romania Sapphire|Queen Marie of Romania]]<ref name="Christie’s-2003">{{cite web | url = http://www.christies.com/lotfinder/lot/a-magnificent-and-historic-sapphire-pendant-by-4190982-details.aspx?from=salesummery&intObjectID=4190982&sid=46018e0d-dd25-4985-be9a-0e9289b52a30 | title = Lot 382: A MAGNIFICENT AND HISTORIC SAPPHIRE PENDANT, BY CARTIER | date = 19 November 2003 | location = Geneva, Switzerland | work = Christie’s | access-date = 7 August 2017 | archive-date = 7 August 2017 | archive-url = https://web.archive.org/web/20170807232803/http://www.christies.com/lotfinder/lot/a-magnificent-and-historic-sapphire-pendant-by-4190982-details.aspx?from=salesummery&intObjectID=4190982&sid=46018e0d-dd25-4985-be9a-0e9289b52a30 | url-status = live }}</ref>
| Sri Lanka
| 478.68 carats
| Cushion
| Blue
| Anonymous owner
|-
!scope="row"| [[The Star of Adam|Star of Adam]]<ref name="Sivaramakrishnan-2016"/>
| Sri Lanka, 2015
| 1404.49 carats
| Star
| Blue
| Anonymous owner
|-
!scope="row"| [[Star of Bombay]]
| Sri Lanka
| 182 carats
| Star
| Blue-violet
| National Museum of Natural History, Washington, D.C.
|-
!scope="row"| [[Star of India (gem)|Star of India]]
| Sri Lanka
| 563.4 carats
| Star
| Blue-gray
| [[American Museum of Natural History]], New York
|-
!scope="row"| [[Stuart Sapphire]]
| Sri Lanka
| 104 carats
| 
| Blue
| [[Tower of London]]
|}
Extensive tables listing over a hundred important and famous rubies and sapphires can be found in Chapter 10 of ''Ruby & Sapphire: A Gemologist's Guide''.<ref name="Hughes-2017"/>{{rp|380–395}}

==See also==
{{Portal|Minerals}}
* [[Emerald]]
* [[Geuda]]
* [[List of sapphires by size]]

==References==
{{Reflist|30em}}

==External links==
{{Commons category}}
* [https://webmineral.com/data/Corundum.shtml Webmineral.com], Webmineral Corundum page, Webmineral with extensive crystallographic and mineralogical information on Corundum
* {{Cite EB1911|wstitle=Sapphire |short=x}}

{{Gemstone}}
{{Named sapphires}}
{{Jewellery}}
{{Authority control}}

[[Category:Aluminium minerals]]
[[Category:Corundum gemstones]]
[[Category:Crystals]]
[[Category:Dielectrics]]
[[Category:Minerals in space group 167]]
[[Category:Optical materials]]
[[Category:Oxide minerals]]
[[Category:Superhard materials]]
[[Category:Transparent materials]]
[[Category:Trigonal minerals]]
[[Category:Symbols of Queensland]]