On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Cat’s-eye Chrysoberyl
Also known asChrysoberyl cat’s-eye · Cymophane
Chrysoberyl showing the cat’s-eye effect. To avoid confusion with the effect name, the trade name should spell out the full mineral name. 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 Cat’s-eye Chrysoberyl 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 Cat’s-eye ChrysoberylIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of Cat’s-eye Chrysoberyl1 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing Cat’s-eye ChrysoberylCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of Cat’s-eye ChrysoberylEach value with its source and check date
- Cat’s-eye Chrysoberyl 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: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Listing and disclosing Cat’s-eye ChrysoberylThe listing name to use; what must be disclosed before sale
- Standard clauses that define Cat’s-eye ChrysoberylWhich 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
Cat's-eye chrysoberyl is the chatoyant variety of chrysoberyl (BeAl2O4). Its eye comes from parallel needle-like inclusions within the crystal — in chrysoberyl these are rutile almost without exception, with ilmenite rare. The needles are thought to arise by exsolution-precipitation of titanium that was originally dissolved in the chrysoberyl lattice, oriented along directions such as [100], <110> and [001]. The needles scatter light, and the cabochon-cut surface focuses the scattered light into a bright line that moves as the stone rotates — the cat's-eye. Where no mineral species is named, 'cat's-eye' refers by default to cat's-eye chrysoberyl.
Scope: Covers the cat's-eye effect mechanism of chrysoberyl; asterism and cat's-eyes in other minerals are outside the scope of this record.
Sources G&G Summer 2025
Where it forms
Be-bearing systems such as granitic pegmatites, where chrysoberyl hosts exsolved needle inclusions that produce the eye.
Sources G&G Summer 2025
How it forms, step by step
Chrysoberyl crystallises in a Ti-bearing system, incorporating titanium into its structure.
On cooling, titanium exsolves-precipitates as rutile needles aligned along specific crystallographic directions.
The parallel needles scatter light, and a cabochon cut focuses the scattered light into the cat's-eye line.
Link to appearance
Parallel needle inclusions give chrysoberyl a cat's-eye under cabochon cutting; finer, denser needles generally yield a sharper eye.
Sources G&G Summer 2025
Timescale
Needle inclusions exsolve on cooling after crystallisation; timing depends on the cooling history.
Sources G&G Summer 2025
Related base materials
- Chrysoberyl: Mineral parent: this variety belongs to the mineral species chrysoberyl (BeAl2O4)
Supporting findings
As chrysoberyl, cat's-eye chrysoberyl occurs in Be-bearing systems such as granitic pegmatites.
Evidence grade AScope: Describes the pegmatite setting without excluding others.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Tunduru, TanzaniaNamed as a new chrysoberyl source; cat's-eye not singled out
Sources Gems & Gemology Winter 2000
- Ilakaka, Madagascar
Sources Gems & Gemology Winter 2000
Asia
- Sri LankaMajor source of chrysoberyl including cat's-eye
Sources Gems & Gemology Winter 2000
- Odisha, IndiaGreen cat's-eye chrysoberyl
Sources Gems & Gemology Winter 2000
- Andhra Pradesh, IndiaGreen cat's-eye chrysoberyl
Sources Gems & Gemology Winter 2000
South America
- BrazilMajor source of chrysoberyl including cat's-eye
Sources Gems & Gemology Winter 2000
These are localities recorded by authoritative sources, not an origin finding for any individual piece. The CIBJO Gemstone Book (2022, §4.2.3) says a place of origin names where a gem was mined or harvested, is a matter of opinion, does not imply a level of quality, and that cutting, processing or exporting centres must not be used to imply origin. See how far testing can go on this page, the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
Chatoyancy forms when parallel needle-like inclusions scatter light that a cabochon surface focuses into a bright line.
Evidence grade AScope: Describes the cat's-eye (one-dimensional needle) mechanism, not asterism.
In natural chrysoberyl, rutile makes up nearly all of the needle inclusions, forming through exsolution-precipitation of titanium that was dissolved in the structure.
Evidence grade AScope: The rare exception is ilmenite needles in a four-rayed star from Sri Lanka.
How it is identified
Cat's-eye chrysoberyl can resemble other cat's-eye gems, and appearance cannot separate them. Identification, and the judgement of whether it is synthetic or treated, require laboratory testing of composition, spectra and internal features with instruments; the conclusion should be issued by an accredited body.
Evidence grade AScope: Cat's-eye chrysoberyl identification requires a professional laboratory, with the conclusion from an accredited body.
Sources CIBJO Gemstone Book 2022
Other research findings
When the mineral species is not specified, 'cat's-eye' refers by default to cat's-eye chrysoberyl.
Evidence grade AScope: A naming convention; cat's-eyes of other minerals must carry the species name.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The control on needle-inclusion orientation is not fully resolved in the literature.
- Synthesis of cat's-eye chrysoberyl is outside the formation scope.
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
- Cat's-eye Chrysoberyl
GB/T 16552—2017 5.3.1 · IMA Mineral List 2026-07 “Chrysoberyl”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Irradiated (via parent material)
Related:Disclosure and cautions
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
Cat’s-eye Chrysoberyl is Chatoyant chrysoberyl; use "Cat's-eye Chrysoberyl" for listings, and disclose any known treatments.
Evidence
- GB/T · 5.3.1
What this means for you
Before buying, check the recommended listing name "Cat's-eye Chrysoberyl" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- Last reviewed
- 2026-09-01
Care and wear
Care
Cat’s-eye Chrysoberyl — care (special care): irradiated to change colour: normal care; if neutron-irradiated, follow the safety rules under the irradiation code.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- irradiation
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.VIII, Gemstone Information Chart, Chrysoberyl Cat’s Eye R, CARE REQUIRED / SPECIAL ADVICE (locator checked 2026-09-28)
- 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.
Treatments and identification leads
Registered treatmentsThe treatment registered for Cat’s-eye Chrysoberyl is irradiation, with the status irradiated or dyed. Values not givenStability and prevalence are both registered as “—”, meaning the cited source gives no value, not “none”. Identification cluesThe identification lead is that irradiation can improve the cat's-eye effect and colour while being hard to detect; the registered source is the content on irradiation in GB/T 16553—2017. Identification leads are for use when sending a stone for testing and discussing which tests to run.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| irradiationStatus: irradiated or dyed | — | — | Treatment | — | See identification leads |
Where each treatment acts (schematics): Irradiated
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16553—2017; GB/T 16552—2017 Table B.1 (row for Cat’s-eye); JJA/AGL 2025
Whether a treatment has to show in the name differs between the two rule sets (this site’s paraphrase):
- GB/T 16552—2017: a method classed as treatment has to be stated in the name itself — the method put before the name, or added in brackets after it; a method classed as optimization does not need to appear in the name, though one marked “Optimization (annotation required)” still has to be noted in the quality documents. Source: §5.4.2.1 a), b); §5.4.2.2 a)
- CIBJO Gemstone Book 2022: no longer splits treatments into ones that need specific disclosure and ones that need only general disclosure: every treatment is to be disclosed, and the seller tells the buyer which treatment was used and what special care it calls for. Source: §4.2.5 Note 2, §4.2.5.1, pp.14–15
What this table covers
What this page can give
- Registered treatments, their stability and how often they occur (see the table above)
- Identification leads for each treatment, for use when sending a stone for testing
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Cat’s-eye Chrysoberyl, the name register records "Chrysoberyl cat’s-eye" and "Cymophane", for which no restriction on use as a name is recorded (CIBJO Gemstone Book 2022 Annex 8 “Cymophane”); 2 further names in non-Latin scripts are listed in the name register below (2 with no restriction recorded on use as a name).
Names in four languagesCat’s-eye Chrysoberyl has Simplified and Traditional Chinese names, the English name Cat’s-eye Chrysoberyl and Japanese names; the formal name of Japan's GSJ is written as a separate Japanese form. Standard and listing namesOn Chinese standard naming, the original GB/T 16552—2017 does not list this name, and the corresponding name is chrysoberyl cat's-eye; the suggested listing name is Cat’s-eye Chrysoberyl. Trade and mineralogical namesCommon trade names and synonyms are the Chinese short name for cat's-eye and Chrysoberyl cat’s-eye, and the mineralogical name is Chatoyant chrysoberyl. Candidate search termsThe short cat's-eye name is kept only as a candidate search term, and the related high-risk name is the Chinese term for cat's-eye stone. Institution usageThe older English name Cymophane rests on CIBJO Gemstone Book 2022. On authority wording, CIBJO records Cat’s-eye Chrysoberyl (CIBJO Gemmological Laboratories Book 2024); the FTC text on file has no wording for this name, which has been checked; GIA and Gem-A are unchecked, and bodies without a recorded wording show the entry's own English name, which does not represent their position. National standard namesThe formal name in India (BIS) is Chrysoberyl Cat's-eye/Lahsuniya.
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 (4) | ||||
| Chrysoberyl cat’s-eyeEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| CymophaneEnglish | historical name | matched automatically | no restriction recorded | CIBJO Gemstone Book 2022 Annex 8 “Cymophane” |
| 猫眼Simplified Chinese | market name | search candidate only | no restriction recorded | editorial ruling (no clause cited); Note: Related high-risk name “Cat's Eye”. |
| 金绿宝石猫眼Simplified Chinese | synonym | matched automatically | no restriction recorded | GB/T 16552—2017 5.3.1 |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- キャッツアイ／猫目石
- GB/T naming counterpart (this name is not in the standard)
- 金绿宝石猫眼 (GB/T 16552—2017 §5.3.1)
- Mineralogical name
- Chatoyant chrysoberyl
- Trade names and synonyms
- Chrysoberyl cat’s-eye (market name) · Cymophane (historical name)
Four-language names
- 简体中文
- 猫眼金绿宝石
- 繁體中文
- 貓眼金綠寶石
- English
- Cat’s-eye Chrysoberyl
- 日本語
- クリソベリル・キャッツアイ／猫目石
National and regional formal names
- India (BIS)
- Chrysoberyl Cat's-eye / Lahsuniya (लहसुनिया)
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Oxide minerals
- Identity tier
- Mineral / gemstone variety
- Mineral chemical class
- Oxides / hydroxides
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T Table B.1For Cat’s-eye Chrysoberyl, this site applies the "Cat’s-eye" row of GB/T 16552—2017 Annex B, Table B.1: irradiation, category treatment. What Table B.1 is, and how its grades are defined, are on the Gem treatments page. JJA/AGL designationsIn the principal gem names table of the Japanese JJA/AGL Definitions and Nomenclature of Gems and Ornamental Materials, 2025 revision, Chrysoberyl Cat's Eye has the species chrysoberyl, colours yellow, green and brown, a "no treatment" listing, and the note cat's-eye effect; how to read the JJA/AGL table is explained on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Cat’s-eye” row of Table B.1: Irradiation Treatment. The full row, with the effect column, is on the Cat’s-eye page.
What Table B.1 is, and how the “see 5.4.1” grades are defined: see the GB/T 16552: optimization vs treatment page.
JJA/AGL (Japan) table of principal gem names, 2025
This table scrolls sideways on narrow screens.
| Gem name | Species | Colour | Listed in the table | Notes |
|---|---|---|---|---|
| Chrysoberyl Cat's Eye | Chrysoberyl | yellow, green, brown | an untreated tier is listed | chatoyancy |
JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.11
How to read the JJA/AGL table: see the Gem treatments page.
What it is and how it's identified
The composition of Cat’s-eye Chrysoberyl is BeAl2O4, which may contain Fe, Cr and other elements; the structure is crystalline and orthorhombic. Mohs hardness is 8–8.5, and this site notes that hardness alone is not enough to judge durability; there are three directions of imperfect cleavage. Density is 3.71–3.75 g/cm³, derived from the cited clause value of 3.73 with a tolerance of ±0.02. The optic character is anisotropic, biaxial positive; refractive index is 1.74–1.759, derived from the cited clause value of 1.746–1.755 with a tolerance of +0.004/−0.006, and this site notes that the clause has further sub-grades, with the overall value used for registration; birefringence is 0.008–0.01. The UV-visible spectrum shows a strong absorption band at 445nm; as optical effects, both the cat's-eye effect and the colour-change effect can be seen. When untreated, pleochroism is trichroic and weak, in yellow, yellowish green and orange; when untreated, the quality factor (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”.
Definition
Cat’s-eye Chrysoberyl — composition (chemistry): BeAl2O4, elements such as Fe and Cr may be contained.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Structure
Cat’s-eye Chrysoberyl — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — structure (crystal system): orthorhombic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — structure (crystal habit): tabular or granular; pseudo-hexagonal trilling twins
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Cat’s-eye Chrysoberyl — Mohs hardness: 8–8.5
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 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — cleavage: imperfect in three directions
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Cat’s-eye Chrysoberyl — density: 3.71–3.75 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 3.73, with a stated tolerance of ±0.02. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Cat’s-eye Chrysoberyl — optic character: biaxial, optically positive (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — refractive index: 1.74–1.759
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.746–1.755, with a stated tolerance of +0.004 / -0.006. The range shown here is worked out from that.
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — birefringence: 0.008–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — pleochroism: weak trichroism: yellow, yellow-green and orange.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — fluorescence (overall): none; alexandrite cat’s eye: weak to moderate, red.
GB/T 16553—2017
UV fluorescenceredweak–moderate, alexandrite cat’s eyeDots are illustrative colours built from the colour names, not measured values
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — spectrum (UV-visible): 445 nm strong absorption band
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — spectrum (infrared): Chrysoberyl's Be-O and Al-O lattice vibrations produce its diagnostic bands in the mid-IR.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — optical effect (colour change): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cat’s-eye Chrysoberyl — magnification: "silk" inclusions, gas-liquid inclusions, fingerprint-like inclusions, negative crystals.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, colour change
Quality factors
Cat’s-eye Chrysoberyl — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (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): 1.749 / 3.73; Closest values: 1Cobalt Spinel 1.723 / 3.63, 2Grossular 1.745 / 3.9, 3Malachite 1.782 / 3.67, 4Rhodolite 1.755 / 3.9, 5Benitoite 1.78 / 3.65
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
Testing and market
The identification lead for irradiated Cat’s-eye Chrysoberyl is that irradiation can improve the cat's-eye effect and the colour, and is hard to detect. The corresponding treatment state is irradiated or dyed, and the cited source is GB/T 16553—2017, which can be followed for Cat’s-eye Chrysoberyl as a reference only and does not govern it directly. The CIBJO laboratory protocol places Cat’s-eye Chrysoberyl under the “Chrysoberyl” entry; for identification, see the Chrysoberyl entry, and for the list of required tests, see the laboratory testing page.
The CIBJO laboratory protocol covers Cat’s-eye Chrysoberyl under “Chrysoberyl” (§6.1.18): see identification on the Chrysoberyl entry; the required tests are listed on the CIBJO laboratory protocol table for Chrysoberyl.
How far testing can go
Cat’s-eye Chrysoberyl that has undergone irradiation can be identified by the following features: Irradiation can improve the cat's eye effect and the colour; hard to detect.
GB/T 16553—2017
- Treatment state
- irradiated or dyed
- Does this standard apply
- can be followed as a reference only
- Treatment
- irradiation
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.5 (irradiation) (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.
Clause-level definitions
Cat’s-eye Chrysoberyl has a clause-level definition in the CIBJO Gemmological Laboratories Book 2024 under the entry Cat's-eye chrysoberyl, giving the mineral species as chrysoberyl and the mineral/gem variety as cat's-eye chrysoberyl; the CIBJO wording is quoted in full under Clause-level definitions on this page. The cross-check result is a direct CIBJO definition; no identically named English entry was found in this edition of the GB/T annex.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Cat’s-eye chrysoberyl | 7.2.1.43 | Cat’s-eye chrysoberyl is the chatoyant variety of chrysoberyl. Brownish yellow to brown, yellow to yellowish green, black; transparent, translucent, opaque | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
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.
- RRUFF Project, in partnership with the IMA – International Mineralogical Association. IMA Mineral List.
- Geological Survey of Japan, AIST (Japan). Museum mineral specimens, browse by classification.
Further reading
Recorded cultural contexts
Japan's JJA 2021 revised roster lists Chrysoberyl Cat's Eye for February. This records trade-association convention only; it does not establish material identity, natural origin, treatment, provenance, or effect.
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| Publisher or holder | Region | From / period | Source and locator |
|---|---|---|---|
| Japan Jewellery Association | Japan | from 20 December 2021 | Tanjoseki (Japanese birthstone roster, Japan Jewellery Association page; revision of 20 December 2021) 2021 revised birthstone roster, February row: Chrysoberyl Cat's Eye |
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.
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| Page | Content | Status |
|---|---|---|
| Browsing family | Oxide minerals | Live |
| Treatments recorded for this material | Irradiated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Cat’s-eye Chrysoberyl 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.