On this page
UnderstandWhat it is, what people ask, how far this page goes
Artificial products / Manufactured products · Artificial product type · Synthetic product
Synthetic Star Ruby
Also known asLaboratory-grown star ruby
Lab-grown corundum in which the star forms during synthesis; neither qualifier, "synthetic" or "star", may be left out. 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 Ruby 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 RubyIdentification points from the research literature
- Hardness, density and refractive index of Synthetic Star RubyEach value with its source and check date
- Synthetic Star Ruby 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 RubyThe 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
Numbers in curly braces, such as {111}, are crystallographic face symbols (Miller indices): each marks a set of crystal faces or cleavage planes. They are reproduced as written in the cited source.
Synthetic star ruby is man-made red corundum displaying asterism, a synthetic gem variety. It is made by a two-step process: first, growing a titanium-bearing (TiO2) corundum crystal—historically often by a variant of the Verneuil flame-fusion method, adding about 0.1%–0.3% (or up to ~0.52%) TiO2 to the Al2O3 nutrient powder together with chromium for the red colour; second, annealing at 1100–1500°C so that the supersaturated titanium exsolves as rutile (TiO2) needles. These needles are oriented in the basal plane, parallel to three sets of directions along the second-order hexagonal prism a{1120} (the three <1010> directions), intersecting at 60°; they scatter and reflect incident light, forming three intersecting light bands—a six-rayed star. Its asterism is thus the product of manufacture and heat treatment, and the identity must be labelled “synthetic star ruby”, never natural star ruby.
Scope: Applies to man-made red synthetic corundum in which asterism is obtained by a two-step process (Ti-doped growth + annealing to exsolve rutile needles); does not cover other cases in which asterism is created / enhanced on synthetic or natural corundum by diffusion alone.
Sources G&G Fall 2017
Where it forms
An artificial crystal-growth setting: high-temperature melt-growth equipment such as a Verneuil burner, growing corundum single crystals from a doped powder charge in an oxy-hydrogen flame.
Sources G&G Fall 2017
A laboratory heat-treatment setting: after growth, crystals are annealed at 1100–1500°C so dissolved titanium exsolves as rutile needles.
Sources G&G Fall 2017
How it forms, step by step
Grow a titanium-bearing corundum crystal: add TiO2 (about 0.1%–0.3%, historically up to ~0.52%) and a colorant to the Al2O3 nutrient powder and grow a single crystal by the Verneuil flame-fusion method (or a variant).
Anneal to exsolve rutile needles: heat to 1100–1500°C so supersaturated titanium exsolves from the corundum as rutile (TiO2) needles.
Orient the needles and cut a cabochon: the rutile needles lie in the basal plane along three sets of <1010>/second-order hexagonal prism directions intersecting at 60°; cutting a cabochon makes the six-rayed star appear.
Link to appearance
The star’s appearance comes directly from the oriented rutile needles exsolved during annealing: light is scattered and reflected by the three sets of needles intersecting at 60°, producing three intersecting bands that form a six-rayed star; needle length and distribution affect how broad and sharp the rays are, so different production processes and annealing schedules give slightly different star appearances.
Sources G&G Fall 2017
Timescale
The cited sources give example time–temperature scales for this historical process: exsolution annealing at about 1100–1500°C, and about 166 minutes of melting time for a spherical corundum crystal 13 mm in diameter (about 85 minutes in the first stage and 81 minutes in the second). These are process-specific patented figures, not general values.
Sources G&G Fall 2017
Related base materials
- Synthetic ruby: Parent category | Synthetic star ruby is red synthetic corundum showing asterism (a synthetic, artificial product)
- Synthetic corundum: Parent category | Artificially manufactured corundum
- Exsolved rutile (TiO2) needles: Artificially introduced element for producing the star lines | Needles exsolved in oriented fashion during annealing cause the asterism, rather than natural mineralisation
Supporting findings
Making asteriated synthetic (star ruby/sapphire) corundum is based on a two-step process: first producing titanium-bearing corundum crystals, then forming (exsolving) rutile precipitates.
Evidence grade AScope: A summary of historical patented processes (Linde/Wiede’s); specific parameters differ between producers.
Such synthetic star corundum was historically grown mainly by the Verneuil flame-fusion method (or a variant): a single crystal is grown from an Al2O3 powder charge doped with TiO2 (about 0.1%–0.3%, up to ~0.52%) and a colorant.
Evidence grade AScope: A description of historical production; the Ti content varies by patent/producer.
Causes of colour and optical effects
The star is caused by exsolved needle-like precipitates in the crystal that scatter and reflect incident light, forming the three intersecting light bands of a six-rayed star.
Evidence grade AScope: Concerns the optical mechanism of the star; the quantitative relation of ray intensity is not covered.
Annealing, at 1100–1500°C, exsolves needles of rutile; in synthetic star rubies and sapphires these lie within the basal plane, aligned with the second-order hexagonal prism a{1120} (the three <1010> directions), and meet one another at 60°.
Evidence grade AScope: The crystallographic orientation holds for both natural and synthetic corundum; the temperature range is a specific annealing-process value.
How it is identified
The colour and asterism of synthetic star ruby can resemble natural star ruby, making visual distinction unreliable, and internal features such as curved growth striations may require magnification to see. Identification relies on laboratory instruments: microscopic and immersion examination can reveal curved growth striae, gas bubbles, or flux residues, while UV-visible spectroscopy, infrared spectroscopy, and trace-element analysis such as LA-ICP-MS help determine whether a stone is synthetic and how it was grown. Whether a stone is synthetic must be concluded by an accredited laboratory, and this entry provides no threshold for self-identification or separation.
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 threshold.
Origin determination concerns natural material, whereas synthetic star ruby 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
Stones displaying asterism are described with “star/asteriated/asteria” plus the correct name—an example being “synthetic star ruby”; its identity must be clearly labelled as synthetic.
Evidence grade AScope: CIBJO’s rules on asterism naming and synthetic-stone naming; no specific locality involved.
Sources CIBJO Gemstone Book 2022
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The two-step process and annealing temperatures come from a GIA literature study of historical patented processes associated with specific producers (Linde, Wiede’s Carbidwerk, etc.) and are not a general process for all synthetic star corundum today.
- Rutile needle length and distribution vary with process; the resulting differences in star appearance are not quantified here.
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 Ruby
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 Ruby" 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 Ruby" 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 Ruby
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Synthetic Star Ruby, the name register records "Laboratory-grown star ruby", for which no restriction on use as a name is recorded.
Standard and listing namesSynthetic Star Ruby is the name formed under the naming rules of GB/T 16552—2017, with the basic name ruby; the original does not list it separately. The suggested listing name is Synthetic Star Ruby. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Synthetic Star Ruby) and Japanese. Trade and mineralogical namesThe market name/synonym is Laboratory-grown star ruby, registered on the page as a market name; the mineralogical name is described in English as laboratory-grown corundum in which the star is produced during synthesis. Institution usageOn authority wording, the FTC text on file has no wording for this name (checked), and GIA, CIBJO and Gem-A are all unchecked; bodies without a record show the entry's own English name, which does not represent their position. Japanese namesThe GSJ (Japan) wording for the entry's own Japanese name is not yet verified by this site.
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 rubyEnglish | 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・ルビー (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)
- 合成星光红宝石 (GB/T 16552—2017 §5.3.2; basic name 红宝石)
- Mineralogical name
- Laboratory-grown corundum with synthetic asterism
- Trade names and synonyms
- Laboratory-grown star ruby (market name)
Four-language names
- 简体中文
- 合成星光红宝石
- 繁體中文
- 合成星光紅寶石
- English
- Synthetic Star Ruby
- 日本語
- 合成スター・ルビー
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
The material facts for Synthetic Star Ruby are registered for synthetic ruby (the whole class); they are not data measured on Synthetic Star Ruby on its own. As registered for synthetic ruby (the whole class): the structure is crystalline, trigonal, with flame-fusion crystals forming rods, flux-grown crystals rhombohedra and hydrothermal crystals tablets; Mohs hardness is 9, with no cleavage; density is 3.95–4.05 g/cm³ (the cited clause gives 4.00 with a stated tolerance of ±0.05, from which the limits are derived); refractive index is 1.757–1.779 (the cited clause gives 1.762–1.770 with a stated tolerance of +0.009, −0.005, from which the limits are derived); birefringence is 0.008–0.01; the optic character is anisotropic, uniaxial, negative; and 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”.
Chemical composition, long-wave UV luminescence, short-wave UV luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for synthetic ruby (the whole class), so they are not repeated on the Synthetic Star Ruby page; see the material facts on the Synthetic Ruby 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 Ruby (how to read class-level values).
Structure
Synthetic Star Ruby — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — structure (crystal habit): rods (flame fusion); rhombohedra (flux melt); plates (hydrothermal growth).
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Synthetic Star Ruby — 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 ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Synthetic Star Ruby — density: 3.95–4.05 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
- Qualification
The clause we cite gives 4.00, with a stated tolerance of ±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): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Synthetic Star Ruby — optic character: uniaxial, optically negative (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — refractive index: 1.757–1.779
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (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): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — birefringence: 0.008–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — pleochroism: strong, purple-red and orange-red
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Synthetic Star Ruby — optical effect (asterism): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- asterism
Quality factors
Synthetic Star Ruby — quality factor (lustre): vitreous to subadamantine
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- synthetic ruby (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.4.2 (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; 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 Ruby 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.