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Artificial products / Manufactured products · Artificial product type · Synthetic product
Synthetic Corundum
Synthetically made corundum; GB/T 16552-2017 Annex A Table A.4 lists it as "synthetic corundum", and the name must disclose its synthetic nature up front. This page compares how the major standards and institutions name it, what must be disclosed when selling it, whether it can be worn every day, how it is treated and identified, and which source each conclusion comes from.
Price, rarity and origin are outside the scope of this wiki.
What this page can answer
This page covers
- How Synthetic Corundum forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify Synthetic CorundumIdentification points from the research literature
- Caring for and wearing Synthetic CorundumCleaning, heat, chemicals and light, as the cited sources give them
- Hardness and refractive index of Synthetic CorundumEach value with its source and check date
- Synthetic Corundum in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name, names in national standards; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Listing and disclosing Synthetic CorundumThe listing name to use; what must be disclosed before sale
- Standard clauses that define Synthetic CorundumWhich clause defines it, each cross-checked
What we cannot conclude
- Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.
- Geographic origin, unless an origin report accompanies the item.
- Price, rarity or investment value: this wiki covers naming and disclosure only.
Material research: formation, causes and history
What authoritative sources say about how this material forms, what causes its colour and optical effects, where its name comes from and how people have used it. Each statement carries an evidence grade and its sources; it describes the material in general, not any specific piece.
How it forms
Synthetic corundum is corundum produced by human means and, in CIBJO's terms, a "synthetic stone": it matches natural corundum in chemical composition, physical properties and structure yet owes nothing to natural geology. Instead it is grown as single crystals through melt-growth techniques, the Verneuil (flame-fusion) or Czochralski (pulled) method among them, starting from an Al2O3 nutrient charge that colouring oxides may dope. Its identity must always carry the qualifier "synthetic", "laboratory-grown" or "laboratory-created" and must never be presented as natural corundum. Synthetic ruby and synthetic sapphire fall under synthetic corundum as their parent class.
Scope: Applies to the higher-level definition of synthetic corundum, which is artificially manufactured and identical in composition and structure to natural corundum; does not address specific growth process parameters, nor is it used to determine the authenticity of any finished piece.
Sources G&G Fall 2017 · CIBJO Gemstone Book 2022 · G&G Spring 2020
- Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany (Gems & Gemology, Fall 2017, Vol. 53, No. 3)
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022)
- A Quantitative Description of the Causes of Color in Corundum (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
Where it forms
An artificial crystal-growth setting: high-temperature melts (e.g., the oxy-hydrogen flame of a Verneuil furnace) and laboratory/factory crystal-growth and heat-treatment equipment, not a natural geological environment.
Sources G&G Fall 2017 · CIBJO Gemstone Book 2022 · G&G Spring 2020
- Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany (Gems & Gemology, Fall 2017, Vol. 53, No. 3)
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022)
- A Quantitative Description of the Causes of Color in Corundum (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
How it forms, step by step
Prepare the nutrient charge: a high-purity Al2O3 powder base doped as needed with colouring oxides (e.g., Cr2O3 for red, Fe and Ti for blue).
Grow a single crystal by a melt method: melt the charge and crystallize corundum single crystal (boules) using the Verneuil flame-fusion or Czochralski pulling technique.
Anneal and fashion: heat-treat as required, then cut and polish the finished stone.
Link to appearance
The appearance of synthetic corundum is set by the colouring elements deliberately added: Cr yields red (corresponding to ruby), Fe–Ti yields blue (corresponding to sapphire). Because composition and structure match natural corundum, gemological properties such as refractive index, birefringence and hardness are also similar; the difference lies mainly in origin and internal features.
Sources CIBJO Gemstone Book 2022
Timescale
The cited sources give an example of production timescale for historical synthetic (star) corundum: a spherical crystal 13 mm in diameter was quoted at about 166 minutes of melting time; this is a specific process figure and is not a general timescale for all synthetic corundum.
Sources G&G Fall 2017 · CIBJO Gemstone Book 2022 · G&G Spring 2020
- Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany (Gems & Gemology, Fall 2017, Vol. 53, No. 3)
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022)
- A Quantitative Description of the Causes of Color in Corundum (Gems & Gemology, Spring 2020, Vol. 56, No. 1)
Related base materials
- Corundum (Al2O3): Synthetic counterpart: chemical composition, physical properties and structure are essentially identical to natural corundum, but it is man-made
- Alumina (Al2O3) nutrient powder: Raw material/precursor for artificial crystal growth; colouring oxides may be added
Supporting findings
Synthetic corundum is manufactured by melt-growth methods: for instance the Verneuil flame-fusion technique (growing from an Al2O3 powder charge doped with TiO2) or the Czochralski pulling method, growing corundum single crystals from a melt.
Evidence grade AScope: The two methods are examples; other melt-growth or flux methods can also produce synthetic corundum.
How it is identified
Synthetic corundum can be nearly indistinguishable from natural corundum by eye, especially when diagnostic internal features are absent. The separation rests on trace-element chemistry: a laboratory uses instruments such as energy-dispersive X-ray fluorescence to measure which trace elements occur and at what level, since certain elements (those introduced by flux or crucible, for example) appear only in synthetic stones, and microscopy of growth features is used alongside. The conclusion must come from an accredited laboratory, and the method needs specialist instruments.
Evidence grade AScope: Synthetic corundum determinations must be issued by an accredited laboratory with specialist instruments; this entry is not self-identification.
Synthetic corundum is man-made corundum. Such material is man-made, so natural origin determination does not apply. Origin determination is meaningful only for natural stones: for synthetic material the synthesis or treatment status has to be settled first, and a place name attached to it is at most a brand or a place of manufacture, not a geological source. Any separation of species or naturalness must be issued by a qualified laboratory for a specific specimen, and origin cannot be inferred from appearance or name.
Evidence grade AScope: Origin cannot be inferred from appearance or name; an origin conclusion must be issued by a qualified laboratory for a specific specimen, and this entry provides no self-test criteria or thresholds.
Sources G&G Winter 2019 · G&G Summer 1998 · G&G Spring 2015 +1
- Geographic Origin Determination of Ruby (Gems & Gemology, Winter 2019, Vol. 55, No. 4)
- Separating Natural and Synthetic Rubies on the Basis of Trace-Element Chemistry (Gems & Gemology, Summer 1998, Vol. 34, No. 2)
- Mozambique Ruby Discovery: A 21st Century Rush (Gems & Gemology, Spring 2015, Vol. 51, No. 1)
- Sapphire Beneath the Rich Black Soil of Muling, Northeastern China (Gems & Gemology, Fall 2022, Vol. 58, No. 3)
Other research findings
Synthetic corundum is an artificial, man-made product — a "synthetic stone" — whose chemical composition, physical properties and structure match natural corundum's essentially; its name must therefore be qualified with "synthetic", "laboratory-grown" or "laboratory-created".
Evidence grade AScope: Uses CIBJO’s general definition and naming rule for synthetic stones; no brand or locality involved.
Sources CIBJO Gemstone Book 2022
Commercially available synthetic stones include synthetic ruby and synthetic sapphire, all made by a synthetic (man-made) method and corresponding to a natural gemstone.
Evidence grade AScope: The commercially available synthetic stones are CIBJO’s examples, not an exhaustive list.
Sources CIBJO Gemstone Book 2022
Because it matches natural corundum in composition and structure, synthetic corundum has similar gemological properties; separating natural from synthetic relies mainly on internal growth features rather than basic physical properties.
Evidence grade AScope: Rests on the definitional fact of identical composition/structure; specific identification features are not enumerated.
Sources CIBJO Gemstone Book 2022
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Synthetic/man-made information comes from the CIBJO definition and GIA laboratory research; details of historical patented processes come from a literature review and do not represent the specific process of all synthetic corundum on the market.
- The growth methods cited (Verneuil, Czochralski) are examples; other melt-growth or flux methods can also produce the same material.
Methodology
- Origin determination and its limits
- Quality grading and value factors
- How gemmology became a technical discipline
Evidence grades
- A
- Standards bodies, government geological surveys, peer-reviewed research and museum records
- B
- Institutional educational material
- C
- Specialist databases or cautious readings
A statement is never graded above its strongest source.
This section is LumaLark's own factual restatement of public authoritative sources, credited item by item; it contains no verbatim excerpts, images or third-party logos.
DecideListing name, disclosure, care and treatments
- Suggested listing name
- Synthetic Corundum
GB/T 16552—2017 Table A.4 “Synthetic Corundum” · CIBJO Gemstone Book 2022 4.3.3.1
This page cannot answer
Natural? · Origin · Price
A lab report settles these; this wiki covers naming and disclosure.
Related:What this page can answer
Answer at a glance
"Synthetic Corundum" is a market name rather than a mineral species name; before using it, verify: Not a mineral: man-made or non-mineral material.
Evidence
- GB/T · Table A.4, row 合成刚玉 (Synthetic Corundum)
What this means for you
Before buying, check the recommended listing name "Synthetic Corundum" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- This entry's exact material identity is not fully settled.
- See “Disclosure and cautions” above
- Last reviewed
- 2026-09-01
Trade-name ruling
- Not a mineral: man-made or non-mineral material.
- Suggested listing name
- Synthetic Corundum
Care and wear
Care
Synthetic Corundum — care (cleaning): for colourless sapphire, natural or synthetic, the GIA 4Cs blog lists ultrasonic and steam cleaning as usually safe; this entry covers colourless material only.
GIA 4Cs blog (2016)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- GIA 4Cs blog, “What Are Simulated Diamonds?” (2016-12-20): Section: main text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
care (wear)2 sources compared
Synthetic Corundum — care (wear): the same entry, covering natural or synthetic colourless sapphire, calls it hard, tough and very durable, suitable for rings.
GIA 4Cs blog (2016)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- GIA 4Cs blog, “What Are Simulated Diamonds?” (2016-12-20): Section: main text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Synthetic Corundum — care (wear): GIA notes that synthetic sapphire is durable enough to serve as window material in supermarket scanners and spacecraft.
GIA Gem Encyclopedia
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- GIA Gem Encyclopedia, “Sapphire”, gia.edu web page: Section: main text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Common care questions and matching entries
Each question links to the matching entries on this page; whether they answer it fully, go by the entry wording.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | for colourless sapphire, natural or synthetic, the GIA 4Cs blog lists ultrasonic and steam cleaning as usually safe; this entry covers colourless material only |
| Wearing limits (knocks, settings) | the same entry, covering natural or synthetic colourless sapphire, calls it hard, tough and very durable, suitable for rings; GIA notes that synthetic sapphire is durable enough to serve as window material in supermarket scanners and spacecraft |
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesThe Chinese standard name for Synthetic Corundum is synthetic corundum, based on GB/T 16552—2017 Table A.4; the suggested listing name is likewise Synthetic Corundum, and the mineralogical name is Synthetic corundum. Names in four languagesNames are registered in four languages: Simplified Chinese, Traditional Chinese, English (Synthetic Corundum) and Japanese. Institution usageOn the wording of GIA, FTC, CIBJO and Gem-A: the FTC and CIBJO texts on file have no wording for this name (checked), and GIA and Gem-A are unchecked; bodies without a recorded wording show the English name of Synthetic Corundum itself, which does not represent their position. Japanese namesThe Japanese name shown is the entry's own; the wording used by the GSJ (Japan) for it is not yet verified by this site. National standard namesAmong national and regional standard names, Germany (RAL) uses Synthetischer Korund and the EU uses Synthetic Corundum.
- GSJ (Japan) formal name
- 合成コランダム (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 合成刚玉 (GB/T 16552—2017 Table A.4)
- Mineralogical name
- Synthetic corundum
Four-language names
- 简体中文
- 合成刚玉
- 繁體中文
- 合成剛玉
- English
- Synthetic Corundum
- 日本語
- 合成コランダム
National and regional formal names
- Germany (RAL)
- Synthetischer Korund
- European Union
- Synthetic Corundum
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Artificial products / Manufactured products
- Material domain
- Artificial products / Manufactured products
- Browsing family
- Synthetic gem products
- Identity tier
- Artificial product type
- Mineral chemical class
- Mixed / composition-dependent
- Construction or treatment status
- Synthetic product
What it is and how it's identified
Material facts for Synthetic Corundum are registered from GB/T 16553—2017: structure (overall) crystalline, crystal system trigonal; site note: GB/T 16553 has no separate entry for synthetic corundum, but its two entries for synthetic ruby and synthetic sapphire both have synthetic corundum as the material name and describe the structure in the same way, so they are registered together. On durability, Mohs hardness is 9 and there is no cleavage; site note: hardness alone is not enough to judge durability. Optically, optic character is anisotropic, uniaxial, optically negative; refractive index is 1.757–1.779, with a site note that the cited clause gives 1.762–1.770 with a stated tolerance of +0.009, −0.005, from which 1.757–1.779 is worked out; birefringence is 0.008–0.01; the optical effect (asterism) is visible.
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Structure
Synthetic Corundum — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
GB/T 16553 has no separate clause for synthetic corundum.
Its clauses on synthetic ruby and synthetic sapphire (see the source line) both give synthetic corundum as the material name and word this item the same way, so it is given once here; for items the two word differently, see the Synthetic Ruby and Synthetic Sapphire entries.
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Synthetic Corundum — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Durability
Synthetic Corundum — Mohs hardness: 9
GB/T 16553—2017
Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, Orthoclase 6–6.5, Topaz 8, Diamond 10 (Source: GB/T 16553—2017); Gypsum 1.5–2, Calcite 3, Quartz 7 (Source: Handbook of Mineralogy); Corundum 9 (Source: GIA Gem Encyclopedia (care guide))
- Does this standard apply
- applies to this entry
- General note
- hardness only, not durability
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Synthetic Corundum — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Optical
Synthetic Corundum — optic character: uniaxial, optically negative (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Synthetic Corundum — refractive index: 1.757–1.779
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.762–1.770, with a stated tolerance of +0.009 / -0.005. The range shown here is worked out from that.
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Synthetic Corundum — birefringence: 0.008–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
Synthetic Corundum — optical effect (asterism): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-28
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2, §5.4.3 (locator checked 2026-09-28)
- Fact checked on
- 2026-09-28
- CIBJO definitions
- asterism
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
The clause-level definition for Synthetic Corundum is registered under the term Synthetic Corundum, based on GB/T 16552-2017 Annex A, with the definition written as Synthetic corundum. The cross-check result is that it is listed directly by GB/T, and CIBJO carries no standalone entry under the same name.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Synthetic Corundum | GB/T 16552-2017 Annex A | Synthetic corundum | Listed directly by GB/T; CIBJO carries no standalone entry under the same name. |
Evidence and sources
Authority basis and clause sources
Sources
- CIBJO – The World Jewellery Confederation. Gemmological Laboratories Book (Blue Book), Gemmological Commission 2024-1.
- CIBJO – The World Jewellery Confederation. The Gemstone Book (Blue Book), 2022.
- SAMR / SAC (China). GB/T 16552—2017 Gems — Nomenclature.
- Federal Trade Commission (United States). In the Loupe: Advertising Diamond, Gemstones and Pearls.
Further reading
Related entries and topic cluster
Parent entry and related pages on this site. Rows marked “Planned” are suggested new content and have no link yet.
Related-entry tree for Corundum on this site: 18 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Synthetic Corundum) is marked.
- Corundum
Sub-entries (13)
- Colour-change Sapphire
- Green Sapphire
- Orange Sapphire
- Padparadscha Sapphire
- Pink Sapphire
- Purple Sapphire
- Ruby
Sub-entries (2)
- Lead-Glass-Filled Ruby
- Synthetic Ruby (Synthetic product)
- Sapphire
Sub-entries (2)
- Beryllium-Diffused Sapphire
- Synthetic Sapphire (Synthetic product)
- Star Ruby
- Star Sapphire
- Synthetic Corundum (Synthetic product)
- White Sapphire
- Yellow Sapphire
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Synthetic gem products | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Synthetic Corundum entry are maintained by the LumaLark wiki and matched one by one to the standard clauses or institutional sources they cite: every fact carries its source (with a clause or page locator) and a check date, so it can be traced back to the original; clause-level definitions also carry a cross-check result. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.