On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown
Grossular
Also known asGrossularite
A garnet-group mineral species with calcium and aluminium end-members; hessonite and tsavorite are both colour varieties of it. 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 Grossular 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 GrossularHow far lab testing can go and whether a synthetic exists
- Treatments and enhancements of GrossularThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing GrossularCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of GrossularEach value with its source and check date
- Grossular 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 GrossularThe listing name to use; what must be disclosed before sale
- Standard clauses that define GrossularWhich 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
Grossular — also known as grossularite — is the calcium-aluminium garnet species and one of the five garnet species of commercial importance. Its green varieties, tsavorite and others, occur in metamorphic rocks but need uncommon rock chemistry and special conditions, which is why they are rarer. At Itrafo in central Madagascar, tsavorite and other grossular varieties are recovered from a primary deposit; the samples studied are almost pure grossular (92 mol.%), with iron and vanadium acting as the main chromophores.
Scope: Used to describe the composition and occurrence of grossular as the calcium end-member mineral species of garnet; specific locality data are limited to the Itrafo study.
Sources GIA Garnet Description · G&G Fall 2012
Where it forms
Metamorphic rocks of unusual chemistry: green grossular (tsavorite etc.) needs unusual rock chemistry and special conditions.
Sources GIA Garnet Description · G&G Fall 2012
Primary deposit: at Itrafo, tsavorite and the other grossular varieties come from primary bedrock rather than from placers.
Sources GIA Garnet Description · G&G Fall 2012
How it forms, step by step
Under metamorphic conditions, rocks of a particular bulk chemistry promote grossular crystallization.
Sources GIA Garnet Description · G&G Fall 2012
Iron and vanadium enter the grossular lattice as main chromophores, colouring some grossular green.
Sources GIA Garnet Description · G&G Fall 2012
At Itrafo the grossular is nearly pure (92 mol.%), reflecting the specific chemistry of that primary deposit.
Sources GIA Garnet Description · G&G Fall 2012
Link to appearance
Pure grossular is near-colourless; iron- and vanadium-bearing grossular is green (e.g. tsavorite).
Sources G&G Fall 2012
Timescale
The sources state no absolute age or duration for garnet formation.
Sources GIA Garnet Description
Related base materials
- Garnet group: mineral-group member | Grossular is the calcic end-member mineral species dominated by Ca2+ and Al3+; its iron- and vanadium-bearing material is the tsavorite variety
Supporting findings
Green grossular varieties (e.g. tsavorite) occur in metamorphic rocks but are rarer, needing unusual rock chemistry and special conditions.
Evidence grade AScope: For green grossular varieties; not other colour varieties.
Sources GIA Garnet Description
Tsavorite and other grossular varieties at Itrafo come from a primary deposit; samples are nearly pure grossular (92 mol.%).
Evidence grade AScope: Based on twenty-two Itrafo (Madagascar) samples and a primary deposit.
Sources G&G Fall 2012
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Tsavo National Park area, KenyaTraditional tsavorite locality
Sources GIA Gem Encyclopedia · Gems & Gemology Winter 2000
- Northern TanzaniaTraditional tsavorite locality
Sources Gems & Gemology Winter 2000
- Lindi Region, TanzaniaLarge new tsavorite deposit of the 1990s
Sources Gems & Gemology Winter 2000
- Itrafo, Andrembesoa area, central Madagascar
Sources G&G Fall 2012
- Diakon, Kayes, MaliGrossular-andradite
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
At Itrafo, iron and vanadium are the main chromophores in grossular.
Evidence grade AScope: Chromophore result for Itrafo samples; other localities may differ.
Sources G&G Fall 2012
Other research findings
Grossular is one of the five commercially important garnet species.
Evidence grade AScope: Defines it as a commercial species; no deposit detail.
Sources GIA Garnet Description
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- No absolute age, P-T or deposit-wide data for grossular formation.
- Green varieties are illustrated only by tsavorite and the Itrafo occurrence.
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
- Grossular
GB/T 16552—2017 Table A.1 “Grossularite” · IMA Mineral List 2026-07 “Grossular”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Heated / Heat-treated (via parent material), Filled / Fracture-filled (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
Grossular is Grossular garnet; use "Grossular" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.1, row 钙铝榴石 (Grossular)
What this means for you
Before buying, check the recommended listing name "Grossular" 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
Normal care for every gemstone (CIBJO Gemstone Book §6.1), in brief:
- Handle it gently.
- Store pieces apart when not worn, so they cannot scratch each other.
- Clean with warm soapy water and a soft brush.
- Use ultrasonic cleaners only with caution.
The §6.1 wording and the full list of §6.2 special-care letters cited on this page are on the general gem care page.
The item-by-item care advice that the GIA Care and Cleaning Guide gives for the whole class, and so for Grossular, is set out in full under care on the Garnet entry.
Care
Grossular — care (heat): Some stones are prone to damage due to thermal shock. Do not expose them to extreme temperature changes.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code e
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Grossular, p.55; §6.2 e (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — care (special care): normal care, but avoid sudden temperature change.
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.X, Gemstone Information Chart, Garnet Grossularite 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
HeatGrossular is sensitive to sudden temperature changes. The Official Gemstone Book of the CIBJO Blue Book (Coloured Stone Commission 2022) gives this conclusion for Grossular irrespective of treatment status. The AGTA Gemstone Information Manual, 17th edition, states that untreated Grossular needs only normal care but should be kept away from sudden temperature changes. The care conclusion for heat and thermal shock is therefore sensitivity to sudden temperature changes. General careThe general care that applies to all gems and the full table of special care letters are in the general care part of the materials index page; the GIA care and cleaning guide is given for the whole class and so also applies to Grossular, with its item-by-item advice listed in full in the care part of the Garnet entry.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Heat and thermal shock | care (heat) |
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
- care (heat) §6.2 e
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 | — | — |
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Garnet)
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 Grossular, the name register records "Grossularite", for which no restriction on use as a name is recorded.
Standard and listing namesThe Chinese formal name for Grossular comes from GB/T 16552—2017 Table A.1, and the suggested listing name is Grossular; trade names or synonyms include Grossularite (an older name), and the mineralogical name is Grossular garnet. Names in four languagesFour-language names are given in Simplified Chinese, Traditional Chinese, English (Grossular) and Japanese, and the formal name of Japan's GSJ is written as a separate Japanese form. Institution usageOn authority wording, the wording recorded in CIBJO's Gemmological Laboratories Book 2024 is Grossular; the FTC text on file has no wording for Grossular (checked); GIA and Gem-A are unchecked. Bodies without a recorded wording show the entry's own English name, which does not represent their position.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
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| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| GrossulariteEnglish | historical name | matched automatically | no restriction recorded | editorial ruling (no clause cited); Note: Former name. |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 灰礬柘榴石
- Chinese formal name
- 钙铝榴石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Grossular garnet
- Trade names and synonyms
- Grossularite (historical name)
Four-language names
- 简体中文
- 钙铝榴石
- 繁體中文
- 鈣鋁榴石
- English
- Grossular
- 日本語
- グロッシュラー／灰礬柘榴石
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Garnet-group minerals and gem varieties
- Identity tier
- Mineral species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
For Grossular, this site applies the "Garnet" row of GB/T 16552—2017 Annex B, Table B.1: heating, category optimization; filling, with its grades on the Gem treatments page. The standard does not list Grossular separately; the treatment list is the result of this site applying the "Garnet" row. The full "Garnet" row with the effect column is on the Garnet entry; what Table B.1 is, and how the filling grades are defined, are on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Garnet” row of Table B.1: Heating Optimization; Filling Graded — see §5.4.1, Table 1. The full row, with the effect column, is on the Garnet 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.
What it is and how it's identified
Among the material facts for Grossular, the composition (phase) is registered as grossular (garnet group). The cited clauses register the structure (crystalline, cubic), Mohs hardness 7–8, no cleavage, an isotropic optic character commonly with anomalous extinction, no birefringence, no pleochroism, and a vitreous to subadamantine lustre for garnet (the whole mineral group), not as measurements of Grossular; the pleochroism and lustre findings are limited to the untreated state. The density of Grossular itself is 3.57–3.73 g/cm³, derived from the cited clause value of 3.61 with a tolerance of +0.12/−0.04; there is also an overall value of 3.5–4.3 g/cm³ for garnet (the whole mineral group). The refractive index is 1.73–1.76, derived from the cited clause value of 1.740 with a tolerance of +0.020/−0.010. Transparency ranges from transparent (usually) to opaque; when untreated, the body colour is light to dark green, light to dark yellow to reddish orange, and rarely colourless. Chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are registered for garnet (the whole mineral group); see the Garnet entry.
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 garnet (the whole mineral group), so they are not repeated on the Grossular page; see the material facts on the Garnet entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Grossular (how to read class-level values).
Definition
Grossular — nomenclature status: IMA status A: approved (accepted by the IMA after it was set up in 1958).
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Grossular — composition (phase): grossular (garnet group)
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Grossular — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — structure (crystal system): cubic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — structure (crystal habit): rhombic dodecahedra, tetragonal trisoctahedra, or crystals combining the two forms.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Grossular — 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
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Grossular — density: 3.57–3.73 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 3.61, with a stated tolerance of +0.12 / -0.04. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 Density · Grossular (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Grossular — density: 3.5–4.3 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Grossular — optic character: isotropic, commonly with anomalous extinction
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — refractive index: 1.73–1.76
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.740, with a stated tolerance of +0.020 / -0.010. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 Refractive index · Grossular (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Grossular — birefringence: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — transparency: transparent (usually) to opaque.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Grossular — pleochroism: none
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — fluorescence (overall): grossular: may have weak, orange-yellow.
GB/T 16553—2017
UV fluorescencemay have: orange-yellowweak, grossularDots are illustrative colours built from the colour names, not measured values
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite says this only of near-colourless, yellow and light green grossular.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 Fluorescence (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Grossular — spectrum (UV-visible): iron-coloured hessonite: may have 407 nm absorption band; may have 430 nm 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): §5.1.15 UV-visible spectrum (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Grossular — optical effect (asterism): seen; rare; generally a four-pointed star; occasionally a six-rayed star (almandine).
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Grossular — optical effect (colour change): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
body colour2 sources compared
Grossular — body colour: light to dark green, light to dark yellow to reddish orange, rarely colourless.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Andesine, Zircon, Kyanite and other entries also name green or a greenish colour.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Grossular — body colour: light to dark green, light to dark yellow, orange-red; rarely colourless.
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 Titanite / Sphene, Sphalerite, Celestite / Celestine and other variety clauses also name green or a greenish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 Colour · Grossular (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
How the sources relate
- CIBJO Gemmological Laboratories Book 2024 and GB/T 16553—2017
The two entries list essentially the same colours: light to dark green, light to dark yellow and an orange-leaning red (GB/T 16553—2017 says orange-red, the CIBJO Gemmological Laboratories Book reddish orange), and both note that colourless is rare.
- CIBJO definitions
- asterism, colour change
Quality factors
Grossular — quality factor (lustre): vitreous to subadamantine
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- garnet (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.15 (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): 1.745 / 3.9; Closest values: 1Pyrope 1.728 / 3.9, 2Burma Ruby 1.768 / 4, 3Ceylon Sapphire 1.768 / 4.03, 4Alexandrite 1.749 / 3.73, 5Almandine 1.79 / 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
Testing and market
In the CIBJO laboratory protocol, Grossular is placed under “Garnet”; for identification methods, see the identification section of the Garnet entry, and for the list of required tests, see the laboratory testing page. According to the cited source, no synthetic Grossular is available on the market.
The CIBJO laboratory protocol covers Grossular under “Garnet” (§6.1.38): see identification on the Garnet entry; the required tests are listed on the CIBJO laboratory protocol table for Garnet.
How far testing can go
Grossular — 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
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Grossular has a clause-level definition in the CIBJO Gemmological Laboratories Book 2024 under the entry Grossular, giving the mineral group as garnet, the mineral species as grossular and the IMA status as A, with the CIBJO wording quoted in full under Clause-level definitions on this page; the cross-check result is a direct CIBJO definition, and no identically named English entry was found in this edition of the GB/T annex. Grossular also has an entry under the name Grossular in the IMA Mineral List, cross-checked against the RRUFF/IMA master mineral list (public domain data).
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Grossular | 7.2.1.101 | light to dark green, light to dark yellow to reddish orange, rarely colourless; transparent (usually) to opaque. See also hessonite and tsavorite | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
| Grossular | IMA Mineral List entry | Grossular Ca3Al2(SiO4)3 A 1962 s.p. | 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.
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 | Garnet-group minerals and gem varieties | Live |
| Treatments recorded for this material | Heated / Heat-treated (via parent material), Filled / Fracture-filled (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Grossular 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.