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
Ametrine
Also known asAmethyst-citrine · Bicolour Quartz (conditional name)
A natural variety of Quartz with both Amethyst and Citrine colour zones in one stone; the cause of the two colours must be distinguished between natural, heating and irradiation. 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 Ametrine 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 AmetrineHow far lab testing can go
- Treatments and enhancements of AmetrineThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing AmetrineCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of AmetrineEach value with its source and check date
- Ametrine 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?
- Listing and disclosing AmetrineThe listing name to use; what must be disclosed before sale
- Standard clauses that define AmetrineWhich 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
Ametrine (also called amethyst-citrine) is a bicoloured variety of quartz in which the colours of both amethyst and citrine occur in a single crystal. Its origin can be understood as follows: quartz crystallizes slowly from migrating silica-bearing solutions in rock cavities and vugs; the iron impurity in the quartz forms the purple amethyst colour centre under low-grade radiation, and heating destabilises that colour centre, converting it to the yellow/orange of citrine depending on the oxidation state of the iron. When different parts of one crystal experienced different radiation and heating, a purple and a yellow/orange sector coexist as ametrine. The only known commercial source of natural ametrine is a single deposit in eastern Bolivia (the Anahí mine), which also produces natural amethyst and citrine.
Scope: Applies to an overview of the composition, colour origin and localities of natural ametrine as a bicoloured variety of quartz; the general part of the colour mechanism is based on the general causes of colour in quartz (GIA 1982 study of green quartz), and the sources have not verified Bolivian ametrine sample by sample. Synthetic or treated material is outside the scope of this record.
Sources GIA Ametrine Description · G&G Summer 2016
Where it forms
Quartz crystals that crystallize slowly from silica-bearing solutions in rock cavities and vugs.
Sources GIA Ametrine Description · G&G Summer 2016
Eastern Bolivia (the Anahí mine) — the only known commercial source of natural ametrine.
Sources GIA Ametrine Description · G&G Summer 2016
How it forms, step by step
Silica-bearing solutions crystallize slowly in cavities to form quartz crystals.
Sources GIA Ametrine Description · G&G Summer 2016 · CIBJO Gemstone Book 2022
The iron impurity in the crystal forms the amethyst colour centre under low-grade radiation, giving some sectors a purple colour.
Sources GIA Ametrine Description · G&G Summer 2016 · CIBJO Gemstone Book 2022
Heating destabilises the purple colour centre, producing yellow/orange (citrine) in other sectors, so both colour sectors coexist.
Sources GIA Ametrine Description · G&G Summer 2016 · CIBJO Gemstone Book 2022
Link to appearance
Top-grade ametrine shows a medium-dark to moderately strong orange together with a vivid to strong purple or violetish purple. Stones above five carats tend to carry the deepest saturation, and the trade likes an appealing half-and-half arrangement in which the colour boundary falls sharply at the middle of the cut gem.
Sources GIA Ametrine Description · G&G Spring 1982
Timescale
The sources do not state numeric geological timescales for the formation of natural ametrine or its colour zoning.
Sources GIA Ametrine Description · G&G Summer 2016
Related base materials
- Quartz (SiO2): Ametrine is a bicoloured variety of quartz
Supporting findings
The only known commercial source of natural ametrine is a single deposit in eastern Bolivia (the Anahí mine), which also produces natural amethyst and citrine.
Evidence grade AScope: Locality uniqueness; discovery of new sources is not excluded.
Sources GIA Ametrine Description · G&G Summer 2016
Recorded localities
Authoritative sources name a single or principal locality.
South America
- Anahí mine, Santa Cruz, Bolivia"Only commercial source" is GIA's encyclopedia wording; G&G 2000 also lists the nearby Yuruty mine.
Sources GIA Ametrine Description
- Yuruty mine, Rincón del Tigre, Santa Cruz, Bolivia
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
Ametrine is a variety of quartz in which purple amethyst sectors and yellow to orange citrine sectors occur together, contrasting, within a single crystal.
Evidence grade AScope: Describes the colour zoning; the mechanism is given in this entry's colour-cause finding.
Sources GIA Ametrine Description
The colour of quartz arises from its iron impurity together with radiation and heating: the iron impurity forms the purple amethyst colour centre under low-grade radiation, and heat destabilises that centre to give the yellow/orange of citrine; different conditions in different parts of one crystal yield the bicolour zoning.
Evidence grade AScope: A general mechanism of colour in quartz (after GIA's 1982 green-quartz study); not verified sample-by-sample for Bolivian ametrine.
Sources G&G Spring 1982
Other research findings
Ametrine (amethyst-citrine) is a bicoloured variety of quartz containing the colours of both amethyst and citrine in the same crystal; it is not an independent mineral species.
Evidence grade AScope: Naming and variety classification; CIBJO lists it as Amethyst-Citrine bicolour / Ametrine.
Sources GIA Ametrine Description · CIBJO Gemstone Book 2022
Ametrine is commonly untreated, but may rarely be heated to citrine; CIBJO lists the corresponding treatment entries.
Evidence grade AScope: CIBJO treatment classification; applies to material with documented treatment.
Sources CIBJO Gemstone Book 2022
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The colour-cause finding above is taken from a general account of colour in quartz (GIA's 1982 green-quartz study) and is not verified sample-by-sample for Bolivian ametrine.
- Two GIA documents on ametrine have identical content; this entry cites only one of them to avoid duplicating the same text.
- No numeric geological timescale for natural ametrine formation is given by the sources.
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
- Ametrine
16 CFR Part 23 §23.24, §23.25(b) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.11 “Ametrine”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Heated / Heat-treated (via parent material), Irradiated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material), Coated (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
Natural colour zoning is not the same as heat- or irradiation-induced bicolouring; synthetic imitations are common.
Evidence
What this means for you
Before buying, check the recommended listing name "Ametrine" 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
Ametrine — care (cleaning): Warm soapy water is safe; ultrasonic cleaning is usually fine unless the stone is dyed or fracture-filled; steam cleaning is not advised.
GIA Gem Encyclopedia (care guide)
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- GIA Gem Encyclopedia — Ametrine Care and Cleaning Guide: Section “Cleaning” (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — care (heat): Abrupt temperature changes can crack it; keep it away from heat.
GIA Gem Encyclopedia (care guide)
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- GIA Gem Encyclopedia — Ametrine Care and Cleaning Guide: Section “Stability” (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — care (light): Some of its colours can fade under long exposure to intense light
GIA Gem Encyclopedia (care guide)
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- GIA Gem Encyclopedia — Ametrine Care and Cleaning Guide: Section “Stability” (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — care (chemicals): Hydrofluoric acid, ammonium fluoride and alkaline solutions can damage it.
GIA Gem Encyclopedia (care guide)
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- GIA Gem Encyclopedia — Ametrine Care and Cleaning Guide: Section “Stability” (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — care (wear): Like amethyst and citrine it is Mohs 7 with good toughness and suits all jewellery, rings included; dust is largely quartz, so protect it from scratches.
GIA Gem Encyclopedia (care guide)
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- GIA Gem Encyclopedia — Ametrine Care and Cleaning Guide: Section “Hardness and toughness” (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — care (special care): normal care
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- untreated
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.VII, Gemstone Information Chart, Ametrine N, CARE REQUIRED / SPECIAL ADVICE (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.
Common care questions and matching entries
CleaningThe care entries for Ametrine come from the GIA Gem Encyclopedia care and cleaning guide for ametrine, all registered as covering any treatment state: warm soapy water is safe, ultrasonic cleaning is usually safe except for the few stones that are dyed or fracture-filled, and steam cleaning is not advised; abrupt temperature changes can crack Ametrine, so keep it away from heat; some colours fade under long exposure to intense light; hydrofluoric acid, ammonium fluoride and alkaline solutions can damage Ametrine. WearFor wear, Ametrine, like amethyst and citrine, has a Mohs hardness of 7 and good toughness, so it suits all kinds of jewellery including rings; most dust and grit is quartz, so guard against scratches. The AGTA Gemstone Information Manual, 17th edition, additionally records that untreated Ametrine needs only normal care.
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| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | Warm soapy water is safe; ultrasonic cleaning is usually fine unless the stone is dyed or fracture-filled; steam cleaning is not advised |
| Heat and thermal shock | Abrupt temperature changes can crack it; keep it away from heat |
| Light and display | Some of its colours can fade under long exposure to intense light |
| Contact with acids, alkalis and household chemicals | Hydrofluoric acid, ammonium fluoride and alkaline solutions can damage it |
| Wearing limits (knocks, settings) | Like amethyst and citrine it is Mohs 7 with good toughness and suits all jewellery, rings included; dust is largely quartz, so protect it from scratches |
Care entries by treatment state
The same entries grouped by the treatment state each applies to; each links to its full wording and source. Letters are CIBJO special-care codes, explained on the gemstone care page.
any treatment state
- Warm soapy water is safe; ultrasonic cleaning is usually fine unless the stone is dyed or fracture-filled; steam cleaning is not advised
- Abrupt temperature changes can crack it; keep it away from heat
- Some of its colours can fade under long exposure to intense light
- Hydrofluoric acid, ammonium fluoride and alkaline solutions can damage it
- Like amethyst and citrine it is Mohs 7 with good toughness and suits all jewellery, rings included; dust is largely quartz, so protect it from scratches
untreated
Treatments and identification leads
One row per treatment, with three standards side by side: how often it occurs and how stable it is (CIBJO), its category in GB/T 16552—2017 Table B.1 (this site's paraphrase) and how the JJA/AGL 2025 table lists it. Each CIBJO value links to its entry under “Testing and market”, where the wording and source are given in full.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| Heating | — | — | Optimization | — | — |
| Irradiation | — | — | Optimization | — | — |
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Dyeing | — | — | Treatment | — | — |
| Coating | — | — | Treatment | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Rock Crystal); 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 Ametrine, the name register records "Amethyst-citrine" and "Bicolour Quartz", for which no restriction on use as a name is recorded (JJA/AGL Gemstone Nomenclature 2025 p.10); one further name in a non-Latin script is listed in the name register below (1 with no restriction recorded on use as a name).
Standard and listing namesThe suggested listing name for Ametrine is Ametrine. The GB/T 16552—2017 naming counterpart given in Table A.1 is “Rock Crystal”; the GB/T 16552—2017 text does not list Ametrine itself. Trade and mineralogical namesMineralogically, Ametrine is a natural quartz variety showing both amethyst and citrine colour sectors; its trade name or synonym is Amethyst-citrine. Candidate search termsBicolour Quartz and its Japanese transliteration come from the JJA/AGL gem names handbook 2025 and are both candidate search terms only. Names in four languagesThe four-language names are given in Simplified Chinese, Traditional Chinese, English (Ametrine) and Japanese (a transliteration of Ametrine). Institution usageAmong authority wordings, GIA and CIBJO list Ametrine, CIBJO's source being the Gemmological Laboratories Book 2024; the FTC source document has no wording for Ametrine (checked), and Gem-A has not yet been checked; bodies without a recorded wording are shown with the entry's own English name, which does not represent their position. Japanese namesThe Japanese GSJ formal name has not yet been checked; the entry's own Japanese name is a transliteration of Ametrine.
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 (3) | ||||
| Amethyst-citrineEnglish | synonym | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| Bicolour QuartzEnglish | market name | search candidate only | no restriction recorded | JJA/AGL Gemstone Nomenclature 2025 p.10 |
| バイカラー・クォーツJapanese | transliteration | search candidate only | no restriction recorded | JJA/AGL Gemstone Nomenclature 2025 p.10 |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- アメトリン (not yet checked for this body — the entry's own Japanese name is shown)
- GB/T naming counterpart (this name is not in the standard)
- 水晶 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Natural quartz variety exhibiting both amethyst and citrine colour sectors
- Trade names and synonyms
- Amethyst-citrine (synonym) · Bicolour Quartz (market name; conditional name)
Four-language names
- 简体中文
- 紫黄晶
- 繁體中文
- 紫黃晶
- English
- Ametrine
- 日本語
- アメトリン
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Quartz and chalcedony materials
- Identity tier
- Mineral / gemstone variety
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T 16552-2017, Annex B, Table B.1
Under the “Rock Crystal” row of Table B.1: Heating Optimization; Irradiation Optimization; Filling Graded — see §5.4.1, Table 1; Dyeing Treatment; Coating Treatment. The full row, with the effect column, is on the Rock Crystal 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 |
|---|---|---|---|---|
| Bicolour Quartz | Quartz | violet / yellow | an untreated tier is listed | also called ametrine (amethyst and citrine colours) |
JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.10
How to read the JJA/AGL table: see the Gem treatments page.
What it is and how it's identified
The composition (phase) of Ametrine is quartz, as given in the CIBJO Gemmological Laboratories Book 2024. Registered from GB/T 16553—2017 for rock crystal (the whole class), Ametrine is crystalline and trigonal; Mohs hardness is 7 and there is no cleavage; density is 2.64–2.69 g/cm³, derived from a clause value of 2.66 with a tolerance of +0.03/−0.02; refractive index is 1.544–1.553, birefringence 0.009, and the optic character is anisotropic, uniaxial positive; pleochroism is weak and varies with colour, and the lustre is vitreous, both registered for the untreated state. The body colour, given by CIBJO, is that of a bicoloured quartz variety combining the colours of amethyst and citrine, untreated. This site notes that in Chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions for amethyst, apatite, aragonite and other entries also mention bluish violet or a bluish-violet tint.
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 rock crystal (the whole class), so they are not repeated on the Ametrine page; see the material facts on the Rock Crystal entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Ametrine (how to read class-level values).
Definition
Ametrine — composition (phase): quartz
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Ametrine — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — structure (crystal habit): hexagonal prisms with prominent horizontal striations on the prism faces
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Ametrine — Mohs hardness: 7
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
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Ametrine — density: 2.64–2.69 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
- Qualification
The clause we cite gives 2.66, with a stated tolerance of +0.03 / -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): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Ametrine — optic character: anisotropic material, uniaxial, with positive optic character; a “Bull's eye” interference figure may be present, and Brazil-law twinning is common in amethyst.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — refractive index: 1.544–1.553
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — birefringence: 0.009
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — pleochroism: weak; it depends on the body colour.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — optical effect (asterism): seen; a six-rayed star, common in rose quartz.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Ametrine — body colour: Bi-coloured variety of quartz with amethyst and citrine colours.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Amethyst, Apatite, Aragonite and other entries also name violet or a violetish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, asterism
Quality factors
Ametrine — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- rock crystal (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.16 (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): 1.548 / 2.67; Closest values: 1Agate 1.537 / 2.63, 2Shoushan Stone 1.56 / 2.7, 3Changhua Stone 1.56 / 2.6, 4Bamboo Coral 1.57 / 2.65, 5Synthetic Beryl 1.57 / 2.69
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 CIBJO laboratory protocol covers Ametrine under “Quartz” (§6.1.65): see identification on the Quartz entry; the required tests are listed on the CIBJO laboratory protocol table for Quartz.
How far testing can go
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Ametrine has a direct definition in the CIBJO Gemmological Laboratories Book 2024 under the entry Ametrine; the definition gives the mineral species as quartz and the mineral/gem variety as ametrine, with the CIBJO wording 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.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Ametrine | 7.2.1.11 | Bi-coloured variety of quartz with amethyst and citrine colours | 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.
- GIA – Gemological Institute of America (United States). Gem Encyclopedia.
- Gem-A – The Gemmological Association of Great Britain (United Kingdom).
- GIA – Gemological Institute of America (United States). Gem Encyclopedia: Ametrine.
- eCFR (United States). 16 CFR § 23.24 — Disclosure of treatments to gemstones. 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.
Related-entry tree for Quartz on this site: 74 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Ametrine) is marked.
- Quartz
Sub-entries (57)
- Agate
Sub-entries (1)
- Amethyst
- Ametrine
- Aventurine Quartz
- Aventurine Quartz / Green Aventurine
- Banded Agate
- Black Agate
- Bloodstone / Heliotrope
- Blue Lace Agate
- Carnelian
- Chalcedony
Sub-entries (2)
- Chrysoprase
- Citrine
- Clear Quartz / Rock Crystal
- Coated Quartz
- Colourless to White Quartz (brand name: Azeztulite)
- Crazy Lace Agate
- Dendritic Agate
- Dyed Agate (Treated: dyed)
- Elestial Quartz / Skeletal Quartz
- Eye Agate
- Flower Agate / Cherry Blossom Agate
- Green Quartz
- High-clarity quartz with golden needle-like inclusions
- Included Quartz
- Jasper
Sub-entries (1)
- Madeira Citrine
- Malachite Agate
- Morion / very dark Smoky Quartz
- Moss Agate
- Moss Chalcedony
- Multi-inclusion Quartz
- Onyx (banded chalcedony)
- Phantom Quartz
- Prase
- Prasiolite / Green Quartz
- Quartz Cat’s-eye
- Quartz claimed to be from the Himalayas
- Quartz Crystal
- Quartz with dark needle-like inclusions
- Quartz with fine fibrous inclusions
- Quartz with flower-like inclusions
- Quartz with golden needle-like inclusions
- Quartz with green needle-like inclusions
- Quartzite Jade
- Quartzose Jade
- Red Agate
- Rock Crystal
- Rose Quartz
- Rutilated Quartz
- Sard
- Sardonyx
- Silicified Asbestos
Sub-entries (2)
- Hawk’s Eye
- Tiger’s Eye
Sub-entries (1)
- Smoky Quartz
- Smoky Quartz (brown variety)
- Strawberry Quartz
- Yellow-green Quartz
- Agate
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| Page | Content | Status |
|---|---|---|
| Browsing family | Quartz and chalcedony materials | Live |
| Treatments recorded for this material | Heated / Heat-treated (via parent material), Irradiated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material), Coated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Ametrine 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.