Editing Ruby (section)

{{short description|Variety of corundum, mineral, gemstone}}
{{about|the gemstone|the programming language|Ruby (programming language)|people with the given name|Ruby (name)|annotations above East Asian characters|Ruby character|other uses|Ruby (disambiguation)}}
{{Use American English|date=August 2015}}
{{Use dmy dates|date=March 2024}}
{{Infobox mineral
|boxbgcolor        = #b31b1d
|boxtextcolor      = #ffffff
| name             = Ruby
| image            = File:Corundum-215330.jpg
| imagesize        = 260px
| alt              =
| caption          = A ruby crystal from [[Dodoma Region]], [[Tanzania]]
| category         = [[Oxide minerals|Oxide]] [[minerals]], [[corundum]] [[Mineral variety|variety]]
| formula          = [[aluminium oxide]] with [[chromium]], Al{{sub|2}}O{{sub|3}}:Cr
| molweight        =
| strunz           =
| dana             =
| system           = [[Trigonal]] 
| class            = Hexagonal scalenohedral ({{overline|3}}m) <br/>[[H-M symbol]]: ({{overline|3}}2/m)
| symmetry         = ''R''{{overline|3}}c<ref>[http://webmineral.com/data/Corundum.shtml Corundum data on Webmineral] {{webarchive |url=https://web.archive.org/web/20071001144657/http://webmineral.com/data/Corundum.shtml |date=1 October 2007}}</ref>
| unit cell        =
| color            = Orangy red through strongly purplish red.
| habit            = Terminated tabular hexagonal prisms
| twinning         =
| cleavage         = No true cleavage
| fracture         = Conchoidal, splintery
| tenacity         = Brittle
| mohs             = 9.0
| luster           = Subadamantine, vitreous, pearly (on partings)
| streak           = White
| diaphaneity      = Transparent, translucent
| gravity          = 3.97–4.05
| density          =
| polish           =
| opticalprop      = Uniaxial/−
| refractive       = n{{sub|ω}}=1.768–1.772 <br/>n{{sub|ε}}=1.760–1.763
| birefringence    = 0.008 to 0.010
| pleochroism      = Strong: purplish-red – orangy-red
| 2V               =
| dispersion       = 0.018
| extinction       =
| length fast/slow =
| fluorescence     = Red under longwave
| absorption       =
| melt             = 
| fusibility       =
| diagnostic       =
| solubility       = 
| impurities       = Cr. (sometimes: Ti, Fe)
| alteration       =
| other            =
| prop1            =
| prop1text        =
| references       =<ref>[https://www.gemdat.org/gem-3473.html Ruby on Gemdat.org] {{webarchive |url=https://web.archive.org/web/20210903162228/https://www.gemdat.org/gem-3473.html |date=3 September 2021}}</ref>
}}
[[File:Rubis gisements.jpg|thumb|upright=1.25|The main ruby-producing countries]]

'''Ruby''' is a [[pink]]ish-red-to-blood-red-colored [[gemstone]], a variety of the [[mineral]] [[corundum]] ([[aluminium oxide]]). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called [[sapphire]]s; given that the rest of the corundum species are called as such, rubies are sometimes referred to as "red sapphires".

Ruby is one of the traditional [[cardinal gem]]s, alongside [[amethyst]], [[sapphire]], [[emerald]], and [[diamond]].<ref>[https://books.google.com/books?id=crc7ZtRHItgC&pg=PA1 ''Precious Stones''] {{webarchive |url=https://web.archive.org/web/20171218182752/https://books.google.com/books?id=crc7ZtRHItgC&pg=PA1 |access-date=18 December 2017}}, Max Bauer, p. 2</ref> The word ''ruby'' comes from ''ruber'', [[Latin]] for red. The color of a ruby is due to the presence of [[chromium]].

Some gemstones that are popularly or historically called rubies, such as the [[Black Prince's Ruby]] in the British [[Imperial State Crown]], are actually [[spinel]]s. These were once known as "Balas rubies".

The quality of a ruby is determined by its color, cut, and clarity, which, along with [[Carat (mass)|carat]] weight, affect its value. The brightest and most valuable shade of red, called blood-red or pigeon blood, commands a large premium over other rubies of similar quality. After color comes clarity: similar to diamonds, a clear stone will command a premium, but a ruby without any needle-like [[rutile]] [[Inclusion (mineral)|inclusions]] may indicate that the stone has been treated. Ruby is the traditional [[birthstone]] for July and is usually pinker than [[garnet]], although some [[rhodolite]] garnets have a similar pinkish hue to most rubies. The world's most valuable ruby to be sold at auction is the [[Estrela de Fura]], which sold for US$34.8 million.<ref>{{Cite web |last=Holland |first=Oscar |date=8 June 2023 |title=Largest ruby ever to come to auction sells for record-breaking $34.8 million |url=https://www.cnn.com/style/ruby-sothebys-auction-record/index.html |access-date=22 September 2023 |website=CNN |language=en |archive-date=22 September 2023 |archive-url=https://web.archive.org/web/20230922031042/https://www.cnn.com/style/ruby-sothebys-auction-record/index.html |url-status=live }}</ref>