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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown
Phenakite
Also known asPhenacite
A mineral species listed in GB/T 16552-2017 Appendix A.1; two English spellings coexist, and the cause of colour and any treatment must be tested. 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 Phenakite 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 PhenakiteHow far lab testing can go and whether a synthetic exists
- Treatments and enhancements of Phenakite1 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing PhenakiteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness, density and refractive index of PhenakiteEach value with its source and check date
- Phenakite in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Name origin and history of PhenakiteWhere the name comes from
- Listing and disclosing PhenakiteThe listing name to use; what must be disclosed before sale
- Standard clauses that define PhenakiteWhich 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
Phenakite is a hexagonal (rhombohedral) beryllium silicate, Be2SiO4. The data sheet records it in pegmatites, greisens, and alpine and hydrothermal veins, where topaz, beryl, chrysoberyl, fluorite, muscovite and quartz accompany it; GIA notes that it occurs both as transparent pegmatitic crystals (Brazil, for instance) and as stream-rounded alluvial pebbles in Sri Lanka. Phenakite occasionally displays a cat's eye: in a Sri Lankan phenakite cabochon studied by GIA, numerous acicular tubes and iridescent platy voids aligned parallel to the optic axis reflected light in a way that produced the pronounced chatoyant band. Synthetic emeralds commonly contain phenakite as a by-product inclusion, and irradiation can give the mineral a brown colour.
Scope: Applies to the composition and occurrence of phenakite as a beryllium silicate mineral, the origin of its chatoyancy (cat's-eye effect) and its irradiation treatment; does not include geochronology of specific deposits.
Sources Handbook of Mineralogy · G&G Summer 2015
Where it forms
Greisen and pegmatite bodies
Sources Handbook of Mineralogy
Hydrothermal and alpine vein systems
Sources Handbook of Mineralogy
Alluvial, stream-rounded pebbles (e.g. Sri Lanka)
Sources G&G Summer 2015
How it forms, step by step
In beryllium-rich pegmatite, greisen, or hydrothermal/alpine vein settings, beryllium and silicon are enriched.
Sources Handbook of Mineralogy
Beryllium and silicon combine to crystallize hexagonal phenakite, intergrown with topaz, beryl, chrysoberyl, fluorite, and quartz.
Sources Handbook of Mineralogy
Some crystals trap acicular tubes and platy voids oriented parallel to the optic axis during growth.
Sources G&G Summer 2015
After weathering and transport, primary crystals become pebbles; when cut and polished, light reflection from the inclusions produces chatoyancy.
Sources Handbook of Mineralogy · G&G Summer 2015
Link to appearance
Phenakite is colorless, yellow, pink, or brown, may be mottled, with vitreous luster; colorless material resembles quartz (hence its name, 'deceiver'). Some specimens show an unusual cat's eye, whose band results from light reflection off acicular tubes and iridescent platy voids parallel to the optic axis.
Sources Handbook of Mineralogy · G&G Summer 2015
Timescale
The source does not state an absolute geological timescale for phenakite formation.
Sources Handbook of Mineralogy · G&G Summer 2015 · CIBJO Gemstone Book 2022
Supporting findings
Phenakite occurs in pegmatites, greisens, and alpine and hydrothermal veins, commonly associated with topaz, beryl, chrysoberyl, fluorite, muscovite, and quartz.
Evidence grade BScope: A general occurrence summary, not a deposit model.
Sources Handbook of Mineralogy
Phenakite occurs naturally as transparent pegmatitic crystals (e.g. Brazil) and as stream-rounded Sri Lankan pebbles, and appears as a by-product inclusion in synthetic emeralds.
Evidence grade AScope: Describes occurrence and its paragenesis as an inclusion in synthetic emeralds.
Sources G&G Summer 2015
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Konso, Southern Ethiopia, Ethiopia
Sources Mindat: Phenakite
Asia
- Ratnapura, Sri LankaAlluvial pebbles suitable for cutting; generally collector stones
Sources G&G Summer 2015 · Mindat: Phenakite
- Momeik Township, Shan State, Myanmar
Sources Mindat: Phenakite
Europe
- Izumrudnye Kopi area, Malyshevo, Sverdlovsk Oblast, Russia
Sources Mindat: Phenakite
North America
- Mount Antero area, Colorado, United States
Sources Handbook of Mineralogy
South America
- Minas Gerais, BrazilTransparent pegmatitic crystals; generally collector stones
Sources G&G Summer 2015 · Handbook of Mineralogy
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
Phenakite's cat's eye is caused by light reflections from numerous acicular tubes and iridescent platy voids aligned parallel to the optic axis.
Evidence grade AScope: For that Sri Lankan cabochon; not all phenakite is chatoyant.
Sources G&G Summer 2015
Where the name comes from
Phenakite's English name comes from a Greek word for 'deceiver', since the colourless mineral resembles quartz.
Evidence grade BScope: Etymology explains the origin of the name only; it does not establish the material's composition, locality, naturalness, or treatment.
Sources Handbook of Mineralogy
Other research findings
Phenakite is a beryllium silicate, Be2SiO4, hexagonal (rhombohedral).
Evidence grade BScope: Ideal composition; natural samples may carry minor Al, Mg, Ca, Na.
Sources Handbook of Mineralogy
The name phenakite derives from the Greek for deceiver, because it resembles quartz when colorless.
Evidence grade BScope: Etymology only.
Sources Handbook of Mineralogy
In the CIBJO standard, Phenakite is listed as a mineral species / gemstone name, commonly untreated but occasionally irradiated to produce brown.
Evidence grade AScope: Confirms nomenclature level and the irradiation treatment record only.
Sources CIBJO Gemstone Book 2022
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The sources give no absolute ages for phenakite formation.
- The specific P-T conditions of phenakite's host lithologies are not quantified in the cited sources.
- CIBJO records occasional irradiation of phenakite to brown, but the treatment frequency and stability details are not further specified.
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
- Phenakite
GB/T 16552—2017 Table A.1 “Phenakite” · IMA Mineral List 2026-07 “Phenakite”
Construction or treatment status
Natural identity; treatment status unknown
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
Phenakite is Phenakite; use "Phenakite" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.1, row 硅铍石 (Phenakite)
What this means for you
Before buying, check the recommended listing name "Phenakite" 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
Phenakite — care (heat): per the same report, high temperatures also remove the colour of yellow-brown phenakite.
Gems & Gemology 2018 (Nikolaev et al.)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- Fact checked on
- 2026-10-06
care (light)3 sources compared
Phenakite — care (light): a 2020 Journal of Gemmology Gem Note likewise states that phenakite's yellow-brown colour bleaches with UV exposure or high heat.
The Journal of Gemmology (Laurs, 2020)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- B.M. Laurs, “Bicoloured Phenakite from Russia”, Gem Notes, The Journal of Gemmology 37(3): 245–246 (2020) (archived excerpt: p. 22 of the issue file): p.246, body text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Phenakite — care (light): oxford's Mineral Susceptibility Database classes phenakite as light-sensitive: red tones may pale to pink, and yellow, orange or brown tones may fade to colourless.
Mineral Sensitivity Database, Oxford (2021)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- K. Royce, “The Mineral Susceptibility Database” (MSD-2021.06), University of Oxford (2021), doi:10.5287/bodleian:r17kVJb7d: Section: main text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Phenakite — care (light): GIA's Gems & Gemology (2018) reports that the colour of tinted, yellow-brown phenakite disappears under ultraviolet exposure or strong heating, since it comes from electron-hole centres; colourless stones are unaffected in colour.
Gems & Gemology 2018 (Nikolaev et al.)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- Fact checked on
- 2026-10-06
Phenakite — care (wear): A 2024 Journal of Gemmology Gem Note says phenakite, though usually regarded as a collector's stone, is tough enough to be worn in jewellery.
The Journal of Gemmology (Evans, 2024)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- C. Evans, “Phenakite from Volodarsk-Volynski, Ukraine”, Gem Notes, The Journal of Gemmology 39(3): 208–209 (2024) (archived excerpt: p. 17 of the issue file): p.209, body 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.
Durability and wearing
Toughness
Brittle
Treatments and identification leads
Registered treatmentsThe treatment registered for Phenakite is irradiation, with status treated, stability stable and market frequency occasional. Values not givenThe identification leads and source for irradiation are registered as “—”, which on this page means the cited source gives no value, not “none”.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| irradiationStatus: treated | occasionally | stable | — | — | — |
Where each treatment acts (schematics): Irradiated
“—” means the cited source gives no value for that item, not “none”. Source: CIBJO Gemstone Book 2022
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 Phenakite, the name register records "Phenacite", for which no restriction on use as a name is recorded.
Standard and listing namesThe Chinese formal name of Phenakite comes from GB/T 16552—2017 Table A.1, and the suggested listing name is likewise Phenakite. Trade and mineralogical namesThe mineralogical name is Phenakite, and the trade name or synonym is Phenacite, recorded as a synonym with no restriction recorded on its use as a name, based on an editorial ruling by this site (no clause cited). Names in four languagesThe four-language names are the Simplified and Traditional Chinese names, English Phenakite and the Japanese names. Institution usageFor authority wording, CIBJO records Phenakite (CIBJO Gemmological Laboratories Book 2024); the FTC text on file has no wording for this name (checked); GIA and Gem-A are unchecked. Bodies without a recorded wording show the entry's own English name for Phenakite, which does not represent their position. Japanese namesPhenakite carries its own Japanese names, and GSJ's wording for this 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) | ||||
| PhenaciteEnglish | synonym | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- フェナカイト／フェナク石 (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 硅铍石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Phenakite
- Trade names and synonyms
- Phenacite (synonym)
Four-language names
- 简体中文
- 硅铍石
- 繁體中文
- 硅鈹石
- English
- Phenakite
- 日本語
- フェナカイト／フェナク石
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Other silicate minerals
- Identity tier
- Mineral species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
The chemical composition of Phenakite registered from GB/T 16553—2017 is Be2SiO4, which may contain Mg, Ca, Al, Na and other elements; structure crystalline, trigonal, with short prismatic crystals formed by rhombohedra alone or by rhombohedra combined with prism faces, and may also form fine-grained aggregates. Mohs hardness 7–8, with one direction of moderate cleavage and one of imperfect cleavage; the site note explains that hardness alone is not enough to judge durability. Density 2.9–3 g/cm³; the cited clause gives 2.95 with a permitted tolerance of ±0.05, and the range is derived from 2.95. Optically, Phenakite is anisotropic, uniaxial, positive, with birefringence 0.016; refractive index 1.65–1.696, where the cited clause gives 1.654–1.670 with a permitted tolerance of +0.026/−0.004, and the range is derived from 1.654–1.670. Transparency is transparent; untreated, lustre is vitreous, pleochroism is weak to moderate and varies with colour, and luminescence is none to weak, in pink, light blue or green.
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
Phenakite — nomenclature status: IMA status G: grandfathered (described before the IMA existed, and generally regarded as a valid species).
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Phenakite — composition (chemistry): Be2SiO4, elements such as Mg,Ca,Al and Na may be contained.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — composition (phase): phenakite
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Phenakite — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — structure (crystal habit): stubby prismatic crystals formed by the rhombohedron alone or by the rhombohedron combined with prism faces; also fine-grained aggregates.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Phenakite — Mohs hardness: 7–8
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 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — cleavage: one direction of moderate cleavage and one of imperfect cleavage
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
For Phenakite, the stability of irradiation is “stable”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- irradiation
- Qualification
This says how well the treatment holds up, not how durable Phenakite itself is.
- General note
- no durability verdict here
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Physical properties
Phenakite — density: 2.9–3 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 2.95, with a stated tolerance of ±0.05. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Phenakite — optic character: uniaxial, optically positive (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — refractive index: 1.65–1.696
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.654–1.670, with a stated tolerance of +0.026 / -0.004. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — birefringence: 0.016
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — transparency: transparent.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Phenakite — pleochroism: weak to moderate, vary from color
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — fluorescence (overall): none to weak, pink, light blue, green.
GB/T 16553—2017
UV fluorescencepinklight bluegreennone–weakDots are illustrative colours built from the colour names, not measured values
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — spectrum (UV-visible): non-characteristic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — spectrum (infrared): diagnostic bands of phenakite in the mid-IR
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Phenakite — magnification: gas-liquid inclusions, mineral inclusions, commonly seen platy mica or aikinite may be visible.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
body colour2 sources compared
Phenakite — body colour: colorless, yellow, light red, brown, etc.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
In chapter 5 of GB/T 16553—2017, the colour entries of Danburite, Titanite / Sphene, Barite and other variety clauses also name colourless.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Phenakite — body colour: Usually colourless to light yellow; may also be light brown, pink, and rarely greenish blue.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Amblygonite, Smithsonite, Kornerupine and other entries also name colourless.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
How the sources relate
- GB/T 16553—2017 and CIBJO Gemmological Laboratories Book 2024
Both list colourless, yellow, brown and a light reddish colour (GB/T 16553—2017 gives yellow, brown and light red; the CIBJO Gemmological Laboratories Book gives light yellow, light brown and pink). The CIBJO Gemmological Laboratories Book adds that it is usually colourless to light yellow and rarely greenish blue.
Quality factors
Phenakite — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.45 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
This material (RI / SG midpoints): 1.673 / 2.95; Closest values: 1Euclase 1.663 / 3.06, 2Datolite 1.646 / 2.95, 3Danburite 1.633 / 3, 4Achroite 1.635 / 2.86, 5Dushan Yu / Dushan Jade 1.63 / 2.9
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
Testing and market
There is no synthetic Phenakite on the market. Among phenakite in circulation, irradiation is occasional, with the status treated. Which tests CIBJO's laboratory rules require for phenakite, and what each method means, are shown in the rules table on the laboratory testing page.
The tests the CIBJO laboratory protocol requires for this material, and what each method means, are in the protocol table on the laboratory testing page: §6.1.60.
How far testing can go
Phenakite — synthetic counterpart on the market: No synthetic counterpart of this material is commercially available
CIBJO Gemstone Book 2022
- Treatment state
- any treatment state
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
For Phenakite in trade, the reported frequency of irradiation is “occasionally”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- irradiation
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Phenakite is defined directly in CIBJO Gemmological Laboratories Book 2024 under the term Phenakite; the visible definition is the mineral species phenakite, IMA status G, with the CIBJO wording quoted in full under Clause-level definitions on this page; the cross-check shows it is defined directly by CIBJO and also appears in the GB/T annex. A clause-level definition for Phenakite also comes from the IMA Mineral List entry, likewise under the term Phenakite, with the definition Phenakite Be2(SiO4) G 1833, cross-checked against the RRUFF/IMA master mineral list and marked as public domain data.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Phenakite | 7.2.1.177 | Usually colourless to light yellow; may also be light brown, pink, and rarely greenish blue; transparent | Defined directly by CIBJO; also present in the GB/T annex. |
| Phenakite | IMA Mineral List entry | Phenakite Be2(SiO4) G 1833 | Cross-checked against the RRUFF/IMA master mineral list (public domain data). |
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.
- GIA – Gemological Institute of America (United States). Gem Encyclopedia.
- Gem-A – The Gemmological Association of Great Britain (United Kingdom).
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.
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| Page | Content | Status |
|---|---|---|
| Browsing family | Other silicate minerals | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Phenakite 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.