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Artificial products / Manufactured products · Artificial product type · Synthetic product
Synthetic Star Sapphire
Also known asLaboratory-grown star sapphire
Lab-grown corundum in which the star forms during synthesis; the "synthetic" and "star" qualifiers must both be equally prominent. 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 Star Sapphire forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- How to identify Synthetic Star SapphireIdentification points from the research literature
- Hardness, density and refractive index of Synthetic Star SapphireEach value with its source and check date
- Synthetic Star Sapphire in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Listing and disclosing Synthetic Star SapphireThe listing name to use; what must be disclosed before sale
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 star sapphire is laboratory-grown corundum with artificial asterism, not a natural deposit product. Its preparation is based on a two-step process: (1) grow titanium-bearing corundum crystals, then (2) form rutile (TiO2) precipitates. The classic method uses the Verneuil (flame-fusion) technique, adding titanium to the alumina powder (as anatase, about 0.1%–0.3% TiO2; Wiede’s Carbidwerk used up to about 0.52%) and growing almost spherical to elliptical boules slowly on an oriented seed; the crystal is then annealed at 1100–1500°C to exsolve oriented rutile needles. The needles scatter and reflect incident light, forming three intersecting bands — a six-rayed star.
Scope: Applies to explaining the laboratory preparation of synthetic star sapphire (Verneuil growth + annealing to exsolve rutile) and the origin of its asterism; does not cover natural mineralisation and is not applicable to natural star sapphire.
Sources G&G Fall 2017
Where it forms
Flame-fusion (Verneuil) furnace: titanium-bearing alumina powder is melted in an oxy-hydrogen flame and corundum is grown slowly on an oriented seed, typically as almost spherical to elliptical boules.
Sources G&G Fall 2017
Annealing furnace: rutile (TiO2) needles are exsolved by annealing between 1100°C and 1500°C.
Sources G&G Fall 2017
Not a natural deposit setting: this material is laboratory-synthesized and involves no magmatic or metamorphic ore-forming environment.
Sources G&G Fall 2017
How it forms, step by step
Titanium is added to the alumina nutrient powder (as anatase, about 0.1%–0.3% TiO2; up to about 0.52% in Wiede’s recipes); adding chromium or iron oxide yields synthetic ruby or blue sapphire, respectively.
Titanium-bearing corundum crystals are grown slowly on an oriented seed by the Verneuil (flame-fusion) method.
The crystal is annealed at 1100–1500°C so that oriented rutile (TiO2) needles exsolve.
A cabochon is cut; the oriented needles scatter and reflect light to produce a six-rayed star.
Link to appearance
Oriented rutile needles exsolved during annealing scatter and reflect incident light, forming three intersecting bands — a six-rayed star that moves with the light source; needle length and density affect how sharp the star appears.
Sources G&G Fall 2017
Timescale
The synthesis has explicit process timescales: Wiede’s annealing was performed between 1100°C and 1500°C, and the melting time for a 13 mm spherical crystal was about 166 minutes (growth in two stages). These are laboratory process times, not natural formation times.
Sources G&G Fall 2017
Related base materials
- Sapphire (corundum): synthetic-counterpart-of | Laboratory-grown synthetic counterpart of sapphire (corundum), not an independent mineral species
- Synthetic corundum / synthetic sapphire: is-a | The star variety among synthetic sapphires
Supporting findings
Asteriated synthetic corundum is made by a two-step process: first grow titanium-bearing corundum crystals, then form rutile (TiO2) precipitates.
Evidence grade AScope: An authoritative account of the synthesis principles, citing both Linde and Wiede’s patents.
Synthetic star rubies and sapphires were grown slowly as almost spherical to elliptical boules by a variant of the Verneuil method, and rutile needles were then exsolved by annealing at 1100–1500°C.
Evidence grade AScope: Describes the Wiede’s Carbidwerk process (mid-1950s to late 1970s), one historical synthesis route.
Causes of colour and optical effects
The star is formed by rutile needle precipitates that scatter and reflect incident light, producing three intersecting light bands (a six-rayed star).
Evidence grade AScope: The optical cause of asterism, common to synthetic and natural asteriated corundum.
How it is identified
The colour and asterism of synthetic star sapphire can resemble natural star sapphire, so visual separation is unreliable and synthetic features often need magnification or instruments to detect. Identification relies on laboratory testing: microscopic and immersion examination reveal internal features such as curved growth striations, gas bubbles, or flux residues, while UV-visible and infrared spectroscopy and trace-element analysis such as LA-ICP-MS help judge synthetic status and growth method. Whether a stone is synthetic must be concluded by an accredited laboratory, and this entry provides no self-identification or separation criteria.
Evidence grade AScope: Safety boundary: appearance and asterism are insufficient to decide synthetic status; determination requires testing by an accredited laboratory, and this entry gives no self-test criteria.
Origin determination concerns natural material, whereas synthetic star sapphire is a man-made synthetic stone, to which natural origin determination does not apply. For such material the treated or synthetic status must itself first be established by an accredited laboratory using instrumental testing; until then an origin discussion is meaningless. Origin cannot be inferred from appearance or name; and even where some natural material is involved, any origin claim must be issued by an accredited laboratory for a specific specimen. No self-test criteria are given here.
Evidence grade AScope: Origin cannot be inferred from appearance or name; natural origin determination does not apply to this material and its treated/synthetic status must first be established by a laboratory; any conclusion must be issued by an accredited laboratory for a specific specimen; no self-test criteria are given here.
Other research findings
The chemistry of synthetic corundum is controlled by doping the powder: about 0.1%–0.3% TiO2 (up to about 0.52% at Wiede’s) to develop asterism, and chromium or iron oxide to produce synthetic ruby or blue sapphire.
Evidence grade AScope: Values come from Linde and Wiede’s patent recipes; doping levels may differ between producers and batches.
Synthetic asteriated corundum shows internal layered growth structure (sequential curved growth layers) and a high concentration of gas bubbles, features useful for distinguishing it from natural material.
Evidence grade AScope: Typical internal/external features of Verneuil-grown synthetic corundum used for identification; not applicable to every synthesis method.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The cited source describes historical synthesis (Linde, Wiede’s and other Verneuil routes, roughly the 1950s–1970s); modern synthetic star sapphire may use different processes.
- This record does not provide quantitative chemical-composition criteria for synthetic star sapphire.
- The timescale cited is laboratory process time (annealing temperature, melting minutes), not a natural formation timescale.
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 Star Sapphire
16 CFR Part 23 §23.25(b), §23.27
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 Star Sapphire" is a market name rather than a mineral species name; before using it, verify: Not a mineral: man-made or non-mineral material.
Evidence
What this means for you
Before buying, check the recommended listing name "Synthetic Star Sapphire" 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 Star Sapphire
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Synthetic Star Sapphire, the name register records "Laboratory-grown star sapphire", for which no restriction on use as a name is recorded.
Standard and listing namesThe name Synthetic Star Sapphire is built by the GB/T naming rules (GB/T 16552—2017, basic name Sapphire) and is not listed separately in the cited text; the suggested listing name is Synthetic Star Sapphire. Names in four languagesThe four-language names are given in Simplified Chinese, Traditional Chinese, English (Synthetic Star Sapphire) and Japanese (a transliteration), the Japanese being the entry's own name; the Japanese GSJ wording for it is not yet verified by this site. Trade and mineralogical namesThe mineralogical name refers to laboratory-grown corundum with synthetic asterism; the trade name or synonym Laboratory-grown star sapphire is registered as a market name, with no restriction on its use as a name recorded. Institution usageOf GIA, FTC, CIBJO and Gem-A, the FTC and CIBJO source texts have no wording for this name (checked), and the wordings of GIA and Gem-A have not been checked; bodies without a recorded wording show the entry's own English name, Synthetic Star Sapphire, which does not represent their position.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| Laboratory-grown star sapphireEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 合成スター・サファイア (not yet checked for this body — the entry's own Japanese name is shown)
- Name built by the GB/T naming rules (not listed as such)
- 合成星光蓝宝石 (GB/T 16552—2017 §5.3.2; basic name 蓝宝石)
- Mineralogical name
- Laboratory-grown corundum with synthetic asterism
- Trade names and synonyms
- Laboratory-grown star sapphire (market name)
Four-language names
- 简体中文
- 合成星光蓝宝石
- 繁體中文
- 合成星光藍寶石
- English
- Synthetic Star Sapphire
- 日本語
- 合成スター・サファイア
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
Among the material facts for Synthetic Star Sapphire, the physical and optical items are written by the cited GB/T 16553—2017 for synthetic sapphire (the whole class), not measured on Synthetic Star Sapphire separately; whole-class features such as chemical composition are given for synthetic sapphire (the whole class); see the Synthetic Sapphire entry. For synthetic sapphire (the whole class), the structure is crystalline and trigonal, with flame fusion producing pear-shaped boules and flux and hydrothermal growth both producing tabular crystals; Mohs hardness 9, no cleavage; density is 3.95–4.1 g/cm³, which this site notes is derived from the cited clause value of 4.00 with a tolerance of +0.10/−0.05; the optic character is anisotropic, uniaxial negative; refractive index is 1.757–1.779, which this site notes is derived from the cited clause value of 1.762–1.770 with a tolerance of +0.009/−0.005; and birefringence is 0.008–0.01. For synthetic sapphire (the whole class), among optical effects asterism can be seen, the colour-change effect can be seen, and the cat's-eye effect can be seen but is uncommon; when untreated, the lustre is vitreous.
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”.
Chemical composition, luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for synthetic sapphire (the whole class), so they are not repeated on the Synthetic Star Sapphire page; see the material facts on the Synthetic Sapphire entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Synthetic Star Sapphire (how to read class-level values).
Structure
Synthetic Star Sapphire — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — structure (crystal habit): pear-shaped boules (flame fusion); plates (flux melt and hydrothermal growth).
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Synthetic Star Sapphire — 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
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Synthetic Star Sapphire — density: 3.95–4.1 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
- Qualification
The clause we cite gives 4.00, with a stated tolerance of +0.10 / -0.05. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Synthetic Star Sapphire — optic character: uniaxial, optically negative (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — refractive index: 1.757–1.779
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
- 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 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — birefringence: 0.008–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — pleochroism: blue: blue and green-blue; green: green and yellow-green; colour-change material: purple and purple-blue; pink: pink and pink-red; orange-yellow: yellow and orange-yellow.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — optical effect (chatoyancy): seen; uncommon
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — optical effect (asterism): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Sapphire — optical effect (colour change): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, asterism, colour change
Quality factors
Synthetic Star Sapphire — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- synthetic sapphire (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
This material (RI / SG midpoints): 1.768 / 4.03; Closest values: 1Rhodolite 1.755 / 3.9, 2Almandine 1.79 / 3.9, 3Grossular 1.745 / 3.9, 4Tsavorite 1.74 / 3.9, 5Spessartine 1.802 / 3.9
Show the full chart (330 registered materials)
Outside the full chart's range, drawn as triangles at the edge (RI / SG midpoints): Hematite 3.045/5.12, Synthetic Rutile 2.76/4.26, Rutile 2.753/4.23, Synthetic Moissanite 2.67/3.22
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.
- GIA – Gemological Institute of America (United States). Gem Encyclopedia.
- eCFR (United States). 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries.
- LMHC – Laboratory Manual Harmonisation Committee. Information Sheets.
- Federal Trade Commission (United States). In the Loupe: Advertising Diamond, Gemstones and Pearls.
- eCFR (United States). 16 CFR § 23.25 — Misuse of the words “ruby,” “sapphire,” “emerald,” “topaz,” “stone,” “birthstone,” “gem,” “gemstone,” etc. In: 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries.
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.
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 Star Sapphire 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. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.