Editing Gemstone (section)

==Synthetic and artificial gemstones==
Synthetic gemstones are distinct from imitation or simulated gems.

Synthetic gems are physically, optically, and chemically identical to the natural stone, but are created in a laboratory.<ref>{{cite book |url=https://books.google.com/books?id=HrESAQAAMAAJ |title=Jewelers' circular-keystone: JCK |date=1994 |publisher=Chilton Company |language=en}}{{full citation needed|date=November 2020}}</ref> Imitation or simulated stones are chemically different from the natural stone, but may appear quite similar to it; they can be more easily manufactured synthetic gemstones of a different mineral ([[spinel#Synthetic spinel|spinel]]), glass, plastic, resins, or other compounds.

Examples of simulated or imitation stones include [[cubic zirconia]], composed of [[zirconium]] oxide, synthetic [[moissanite]], and uncolored, synthetic [[corundum#Synthetic corundum|corundum]] or [[spinel#Synthetic spinel|spinel]]s; all of which are [[diamond simulants]]. The simulants imitate the look and color of the real stone but possess neither their chemical nor physical characteristics. In general, all are less [[Mohs scale of mineral hardness|hard]] than diamond. Moissanite actually has a ''higher'' refractive index than diamond, and when presented beside an equivalently sized and cut diamond will show more "fire".

Cultured, synthetic, or "lab-created" gemstones are not imitations: The bulk mineral and trace coloring elements are the same in both. For example, [[diamond]]s, [[Ruby|rubies]], [[sapphire]]s, and [[emerald]]s have been manufactured in labs that possess chemical and physical characteristics identical to the naturally occurring variety. Synthetic (lab created) [[corundum#Synthetic corundum|corundum]], including ruby and sapphire, is very common and costs much less than the natural stones. Small [[synthetic diamond]]s have been manufactured in large quantities as industrial [[abrasive]]s, although larger gem-quality synthetic diamonds are becoming available in multiple carats.<ref>{{cite web |title=New process promises bigger, better diamond crystals |work=Carnegie Institution for Science |url=http://carnegiescience.edu/news/new_process_promises_bigger_better_diamond_crystals |access-date=7 January 2011 |url-status=live |archive-url=https://web.archive.org/web/20101201005848/http://carnegiescience.edu/news/new_process_promises_bigger_better_diamond_crystals |archive-date=1 December 2010}}</ref>

Whether a gemstone is a natural stone or synthetic, the chemical, physical, and optical characteristics are the same: They are composed of the same [[mineral]] and are colored by the same trace materials, have the same [[Mohs scale of mineral hardness|hardness]] and [[density]] and [[strength of materials|strength]], and show the same [[spectroscopy|color spectrum]], [[refractive index]], and [[birefringence]] (if any). Lab-created stones tend to have a more vivid color since impurities common in natural stones are not present in the synthetic stone. Synthetics are made free of common naturally occurring impurities that reduce gem clarity or color unless intentionally added in order to provide a more drab, natural appearance, or to deceive an assayer.<ref>{{Cite web |last=GIA |date=2011-11-15 |title=What are Synthetic Gemstones? |url=https://4cs.gia.edu/en-us/blog/what-are-synthetic-gemstones-3/ |access-date=2025-05-03 |website=GIA 4Cs |language=en-US}}</ref> On the other hand, synthetics often show flaws not seen in natural stones, such as minute particles of corroded metal from lab trays used during synthesis.<ref>{{Cite web |title=Gemstones - Synthetic and Simulant |url=https://apps.usgs.gov/minerals-information-archives/gemstones/sp14-95/synthetic.html?utm_source=chatgpt.com |access-date=2025-05-03 |website=apps.usgs.gov}}</ref>

=== Types ===
Some gemstones are more difficult to synthesize than others and not all stones are commercially viable to attempt to synthesize. These are the most common on the market currently.<ref name="Weldon">{{cite web |author=Weldon, R. |title=An Introduction to Synthetic Gem Materials |access-date=2023-04-14 |url=http://www.gingermeekallen.com/wp-content/uploads/2014/09/An-Introduction-to-Synthetic-Gem-Materials.pdf |archive-date=April 15, 2023 |archive-url=https://web.archive.org/web/20230415073916/http://www.gingermeekallen.com/wp-content/uploads/2014/09/An-Introduction-to-Synthetic-Gem-Materials.pdf |url-status=live }}</ref>

==== Synthetic corundum ====
Synthetic corundum includes ruby (red variation) and sapphire (other color variations), both of which are considered highly desired and valued.<ref name="Weldon"/> Ruby was the first gemstone to be synthesized by Auguste Verneuil with his development of the flame-fusion process in 1902.<ref>{{Cite journal |last=Shigley |first=James |date=2000 |title=Treated and synthetic gem materials |jstor=24104849 |journal=Current Science |volume=79 |issue=11 |pages=1566–1571}}</ref> Synthetic corundum continues to be made typically by flame-fusion as it is most cost-effective, but can also be produced through flux growth and hydrothermal growth.<ref>{{Cite journal |last=Elwell |first=Dennis |date=1981 |editor-last=Nassau |editor-first=Kurt |title=Synthetic Gemstones |url=https://www.jstor.org/stable/1685235 |journal=Science |volume=211 |issue=4487 |pages=1156 |doi=10.1126/science.211.4487.1156.a |jstor=1685235 |pmid=17755153 |s2cid=239860410 |issn=0036-8075 |access-date=April 15, 2023 |archive-date=April 15, 2023 |archive-url=https://web.archive.org/web/20230415034649/https://www.jstor.org/stable/1685235 |url-status=live }}</ref>

==== Synthetic beryls ====
The most common synthesized beryl is emerald (green). Yellow, red and blue beryls are possible but much more rare. Synthetic emerald became possible with the development of the flux growth process and is produced in this way and well as hydrothermal growth.<ref name="Lefever-1982">{{Cite journal |last=Lefever |first=R |date=1982 |title=Synthetic emerald |journal=American Mineralogist |volume=47 |issue=11–12 |pages=1450–1453 |url=https://pubs.geoscienceworld.org/msa/ammin/article/47/11-12/1450/542016/Synthetic-emerald |access-date=2023-03-15}}</ref>

==== Synthetic quartz ====
Types of synthetic quartz include citrine, rose quartz, and amethyst. Natural occurring quartz is not rare, but is nevertheless synthetically produced as it has practical application outside of aesthetic purposes. Quartz generates an electric current when under pressure and is used in watches, clocks, and oscillators.<ref>{{Cite journal |last1=Hervey |first1=P. R. |last2=Foise |first2=J. W. |date=2001-02-01 |title=Synthetic quartz crystal — A review |url=https://doi.org/10.1007/BF03402862 |journal=Mining, Metallurgy & Exploration |language=en |volume=18 |issue=1 |pages=1–4 |doi=10.1007/BF03402862 |bibcode=2001MMExp..18....1H |s2cid=140031745 |issn=2524-3470}}</ref>

==== Synthetic spinel ====
Synthetic spinel was first produced by accident.{{clarification needed|date=August 2023}} It can be created in any color making it popular to simulate various natural gemstones. It is created through flux growth and hydrothermal growth.<ref name="Weldon"/>

=== Creation process ===
There are two main categories for creation of these minerals: melt or solution processes.<ref name="Weldon"/>

==== Verneuil flame fusion process (melt process) ====
[[File:Verneuil process diagram.svg|thumb|Verneuil furnace]]
The flame fusion process was the first process used which successfully created large quantities of synthetic gemstones to be sold on the market.<ref name="Scheel-2000">{{Cite journal |last=Scheel |first=Hans J |date=2000-04-01 |title=Historical aspects of crystal growth technology |url=https://www.sciencedirect.com/science/article/pii/S0022024899007800 |journal=Journal of Crystal Growth |language=en |volume=211 |issue=1 |pages=1–12 |doi=10.1016/S0022-0248(99)00780-0 |bibcode=2000JCrGr.211....1S |issn=0022-0248 |access-date=April 15, 2023 |archive-date=April 15, 2023 |archive-url=https://web.archive.org/web/20230415031315/https://www.sciencedirect.com/science/article/pii/S0022024899007800 |url-status=live }}</ref> This remains the most cost effective and common method of creating corundums today.

The flame fusion process is completed in a Verneuil furnace. The furnace consists of an inverted blowpipe burner which produces an extremely hot oxyhydrogen flame, a powder dispenser, and a ceramic pedestal.<ref name="Read-1999">{{Cite book |last=Read |first=Peter G. |title=Gemmology |date=1999 |publisher=Butterworth-Heinemann |isbn=0-7506-4411-7 |oclc=807757024}}</ref> A chemical powder which corresponds to the desired gemstone is passed through this flame. This melts the ingredients which drop on to a plate and solidify into a crystal called a ''boule''.<ref name="Read-1999"/> For corundum the flame must be 2000&nbsp;°C. This process takes hours and yields a crystal with the same properties as its natural counterpart.

To produce corundum, a pure aluminium powder is used with different additives to achieve different colors.<ref name="Read-1999"/>

* Chromic oxide for ruby
* Iron and titanium oxide for blue sapphire
* Nickel oxide for yellow sapphire
* Nickel, chromium and iron for orange sapphire
* Manganese for pink sapphire
* Copper for blue-green sapphire
* Cobalt for dark blue sapphire

==== Czochralski process (melt process) ====
In 1918 this process was developed by J. Czocharalski<ref name="Read-1999"/> and is also referred to as the "crystal pulling" method. In this process, the required gemstone materials are added to a crucible. A seed stone is placed into the melt in the crucible. As the gem begins to crystallize on the seed, the seed is pulled away and the gem continues to grow.<ref name="Weldon"/> This is used for corundum but is currently the least popular method.<ref name="Scheel-2000"/>

==== Flux growth (solution process) ====
The flux growth process was the first process able to synthesize emerald.<ref name="Lefever-1982"/> Flux growth begins with a crucible which can withstand high heat; either graphite or platinum which is filled with a molten liquid referred to as flux.<ref name="Scheel-2003">{{Cite book |last=Scheel |first=Hans |title=Crystal Growth Technology |publisher=John Wiley & Sons |year=2003 |isbn=9780470871683}}</ref> The specific gem ingredients are added and dissolved in this fluid and recrystallize to form the desired gemstone.This is a longer process compared to the flame fusion process and can take two months up to a year depending on the desired final size.<ref name="Arem">{{Cite web |last=Arem |first=Joel |title=Understanding Gem Synthetics, Treatments, And Imitations, Part 4: Synthetic Gemstone Guide |website=International Gem Society |url=https://www.gemsociety.org/article/understanding-gem-synthetics-treatments-imitations-part-4-synthetic-gemstone-guide/ |access-date=March 30, 2023 |archive-date=March 22, 2023 |archive-url=https://web.archive.org/web/20230322211822/https://www.gemsociety.org/article/understanding-gem-synthetics-treatments-imitations-part-4-synthetic-gemstone-guide/ |url-status=live }}</ref>

==== Hydrothermal growth (solution process) ====
The hydrothermal growth process attempts to imitate the natural growth process of minerals. The required gem materials are sealed in a container of water and placed under extreme pressure. The water is heated beyond its boiling point which allows normally insoluble materials to dissolve. As more material cannot be added once the container is sealed, in order to create a larger gem the process would begin with a "seed" stone from a previous batch which the new material will crystallize on. This process takes a few weeks to complete.

=== Characteristics ===
Synthetic gemstones share chemical and physical properties with natural gemstones, but there are some slight differences that can be used to discern synthetic from natural.<ref>{{Cite journal |last=Jayaraman |first=A |date= December 28, 2023|title=A brief overview of gem materials: Natural and synthetic |url=https://www.jstor.org/stable/24104848 |journal=Current Science |volume=79 |issue=11 |pages=1555–1565 |jstor=24104848 |via= |archive-date= April 15, 2023 |archive-url=https://web.archive.org/web/20230415034735/https://www.jstor.org/stable/24104848?searchText=&searchUri=&ab_segments=&searchKey=&refreqid=fastly-default:03cfdfcd0fc6ba4823dbdf226c8f4575 |url-status=live }}</ref> These differences are slight and often require microscopy as a tool to distinguish differences. Undetectable synthetics pose a threat to the market if they are able to be sold as rare natural gemstones.{{citation needed|date=April 2024}} Because of this there are certain characteristic gemologists look for. Each crystal is characteristic to the environment and growth process under which it was created.
[[File:Golden Apatite.jpg|thumb|Visible banding in an [[apatite]] gemstone]]
Gemstones created from the flame-fusion process may have

* small air bubbles which were trapped inside the boule during formation process
* visible banding from formation of the boule
* chatter marks which on the surface which appear crack like which are caused from damage during polishing of the gemstone

Gemstones created from flux melt process may have

* small cavities which are filled with flux solution
* inclusions in the gemstone from crucible used<ref name="Li-2001">{{Cite journal |last=Li |first=Zhaolin |date=2001-12-01 |title=Study on inclusions in natural and synthetic gems |url=https://doi.org/10.1007/BF03166857 |journal=Chinese Journal of Geochemistry |language=en |volume=20 |issue=4 |pages=324–332 |doi=10.1007/BF03166857 |bibcode=2001Geoch..20..324L |s2cid=129031255 |issn=1993-0364}}</ref>

Gemstones created from hydrothermal growth may have

* inclusions from container used<ref name="Li-2001" />

=== History ===
[[File:Auguste Victor Louis Verneuil.jpg|thumb|upright|left|Auguste Verneuil – creator of flame-fusion process 1902]]
Prior to development of synthesising processes the alternatives on the market to natural gemstones were imitations or fake. In 1837, the first successful synthesis of ruby occurred.<ref name="Scheel-2000"/> French chemist Marc Gaudin managed to produce small crystals of ruby from melting together potassium aluminium sulphate and potassium chromate through what would later be known as the flux melt process.<ref name="Read-1999"/> Following this, another French chemist Fremy was able to grow large quantities of small ruby crystals using a lead flux.<ref name="Scheel-2003"/>

A few years later an alternative to flux melt was developed which led to the introduction of what was labeled "reconstructed ruby" to the market. Reconstructed ruby was sold as a process which produced larger rubies from melting together bits of natural ruby.<ref name="Arem"/> In later attempts to recreate this process it was found to not be possible and is believed reconstructed rubies were most likely created using a multi-step method of melting of ruby powder.<ref name="Read-1999"/>

Auguste Verneuil, a student of Fremy, went on to develop flame-fusion as an alternative to the flux-melt method. He developed large furnaces which were able to produce large quantities of corundums more efficiently and shifted the gemstone market dramatically.<ref>{{Cite journal |last=Nassau |first=Kurt |date=1990 |title=Synthetic Gem Materials in the 1980s |url=https://www.gia.edu/doc/Synthetic-Gem-Materials-in-the-1980s.pdf |journal=Gems & Gemology |volume=26 |issue=1 |pages=50–63 |doi=10.5741/GEMS.26.1.50 |bibcode=1990GemG...26...50N |access-date=April 15, 2023 |archive-date=November 1, 2021 |archive-url=https://web.archive.org/web/20211101192418/https://www.gia.edu/doc/Synthetic-Gem-Materials-in-the-1980s.pdf |url-status=live }}</ref> This process is still used today and the furnaces have not changed much from the original design.<ref>{{Cite journal |last=Harris |first=Daniel C. |editor-first1=Randal W. |editor-last1=Tustison |date=2003-09-26 |title=A peek into the history of sapphire crystal growth |url=https://www.spiedigitallibrary.org/conference-proceedings-of-spie/5078/0000/A-peek-into-the-history-of-sapphire-crystal-growth/10.1117/12.501428.full |journal=Window and Dome Technologies VIII |publisher=SPIE |volume=5078 |pages=1–11 |doi=10.1117/12.501428|bibcode=2003SPIE.5078....1H |s2cid=109528895 }}</ref> World production of corundum using this method reaches 1000 million carats a year.