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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Trade name: colour / appearance variety · Natural identity; treatment status unknown
Hydrogrossular
A gem material in the hydrous series of grossular, without a single fixed composition; it is listed in GB/T 16552—2017 Table A.2 as "Hydrogrossular". 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 Hydrogrossular forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify HydrogrossularHow far lab testing can go
- Caring for and wearing HydrogrossularCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of HydrogrossularEach value with its source and check date
- Hydrogrossular in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Listing and disclosing HydrogrossularThe listing name to use; what must be disclosed before sale
- Standard clauses that define HydrogrossularWhich 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
None of the cited sources defines hydrogrossular as a mineral species in its own right or as a distinct gem material; the name is therefore handled as a garnet-series material related to grossular. Garnet species form a closely related group in which crystal structure is shared but chemical composition varies; over twenty names exist, of which just five are commercially significant as gems (pyrope, almandine, spessartine, grossular and andradite), and many garnets are, chemically, mixtures of two or more species. Since the sources say nothing that defines "hydrogrossular" itself, this entry does not derive its formation from facts about related species; the material's exact composition and the conditions under which it forms cannot be confirmed from the available sources.
Scope: Used to explain the identity boundary of "hydrogrossular" as a material name within the garnet group related to grossular; formation facts of closely related mineral species such as grossular are not substituted for its definition.
Sources GIA Garnet Description
Where it forms
Garnet-group minerals abound in metamorphic terrains — rock that heat and pressure have altered; red almandine-pyrope garnet occurs on every continent.
Sources GIA Garnet Description
The cited sources give no occurrence or formation setting for 'hydrogrossular' itself; nothing is inferred here.
Sources GIA Garnet Description
How it forms, step by step
Garnet-group minerals crystallize from suitable bulk-rock chemistry under metamorphic conditions (group-level fact).
Sources GIA Garnet Description
The shared garnet lattice accommodates different elements, producing several species and colour varieties.
Sources GIA Garnet Description
'Hydrogrossular' is not separately defined in the cited sources; its exact composition and formation pathway cannot be verified from the available text.
Sources GIA Garnet Description
Link to appearance
The cited sources do not describe the appearance of 'hydrogrossular'; no colour or appearance is inferred under this name.
Sources GIA Garnet Description
Timescale
The cited sources give no formation timescale for 'hydrogrossular'.
Sources GIA Garnet Description
Related base materials
- Grossular garnet (Ca3Al2Si3O12): variety-of
- Garnet group (nesosilicates): group-of | Belongs to the garnet mineral group
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- South Africa
Sources CIBJO Retailers' Reference Guide (2021)
Asia
- Myanmarprinted as Myanmar (Burma)
Sources CIBJO Retailers' Reference Guide (2021)
- China
Sources CIBJO Retailers' Reference Guide (2021)
North America
- Canada
Sources CIBJO Retailers' Reference Guide (2021)
- United States
Sources CIBJO Retailers' Reference Guide (2021)
Oceania
- New Zealand
Sources CIBJO Retailers' Reference Guide (2021)
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.
Other research findings
Garnets constitute a group of species that are closely related, sharing one basic crystal structure while differing in chemical makeup; a given garnet is often, chemically, a mixture of two or more of these species.
Evidence grade AScope: A general description of the garnet group, not a specific definition of 'hydrogrossular'.
Sources GIA Garnet Description
Over twenty species of garnet carry names, yet just five matter commercially for gems — pyrope, almandine, spessartine, grossular and andradite.
Evidence grade AScope: A general species-level framing of garnet, used here to fix grossular as the parent species.
Sources GIA Garnet Description
'Hydrogrossular' is not separately defined as an independent mineral species or gem material in the cited authoritative sources; it should be treated as a garnet-series material name related to grossular.
Evidence grade CScope: A boundary based on an absence in the sources rather than a direct statement; facts about related species must not stand in for its definition.
Sources GIA Garnet Description
Taken together, the cited sources indicate that 'hydrogrossular' should be framed as a garnet-series material name related to grossular rather than an independent mineral species; its definition and formation conditions await authoritative clarification.
Evidence grade CScope: A synthesis rather than a direct source statement, limited by the absence of a definition.
Sources GIA Garnet Description
Limits of this research
- Research status: Only partial material-specific findings found; gaps are stated as gaps
- The cited authoritative sources give no definition, composition or formation conditions for 'hydrogrossular' itself.
- Its identity conclusion rests on an absence in the sources and is a terminology-level judgement, not a mineralogical ruling.
- Facts about grossular or other related species must not stand in for the formation of 'hydrogrossular'.
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
- Hydrogrossular
GB/T 16552—2017 Table A.2 “Hydrogrossular”
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
"Hydrogrossular" is a market name rather than a mineral species name; before using it, verify: Industry-wide term that does not denote a single species.
Evidence
- GB/T · Table A.2, row 水钙铝榴石 (Hydrogrossular)
What this means for you
Before buying, check the recommended listing name "Hydrogrossular" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- This entry's exact material identity is not fully settled.
- See “Disclosure and cautions” above
- Last reviewed
- 2026-09-01
Trade-name ruling
- Industry-wide term that does not denote a single species.
- Suggested listing name
- Hydrogrossular
Care and wear
The item-by-item care advice that the GIA Care and Cleaning Guide gives for the whole class, and so for Hydrogrossular, is set out in full under care on the Garnet entry.
Care
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesThe Chinese formal name for Hydrogrossular comes from GB/T 16552—2017 Table A.2, and the suggested listing name is also Hydrogrossular. Names in four languagesThe four-language names are the Simplified Chinese name, the Traditional Chinese name, the English name Hydrogrossular and the Japanese name; the entry's own Japanese name is shown, and the wording of GSJ (Japan) for this name is not yet verified by this site. Institution usageOn authority wording, the FTC and CIBJO texts on file have no wording for this name (checked), and GIA and Gem-A are unchecked; bodies without a recorded wording show the entry's own English name, Hydrogrossular, which does not represent their position. Trade and mineralogical namesThe mineralogical name refers to a garnet-series material, with the specific name Hydrogrossular, and its identity level is a trade name: a colour or appearance variety.
- GSJ (Japan) formal name
- ハイドログロッシュラー／加水灰礬柘榴石 (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 水钙铝榴石 (GB/T 16552—2017 Table A.2)
- Mineralogical name
- Hydrogrossular garnet-series material
Four-language names
- 简体中文
- 水钙铝榴石
- 繁體中文
- 水鈣鋁榴石
- English
- Hydrogrossular
- 日本語
- ハイドログロッシュラー／加水灰礬柘榴石
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
- Trade name: colour / appearance variety
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
The material facts for Hydrogrossular are registered under GB/T 16553—2017. The chemical formula is Ca3Al2(SiO4)3-x(OH)4x, with some (SiO4) replaced by (OH); it is crystalline or a crystalline aggregate, cubic, with a rhombic dodecahedral crystal habit, and commonly forms granular or massive aggregates. There is no cleavage, and Mohs hardness is 7; this site notes that hardness alone is not enough to judge durability. Density is 3.15–3.55 g/cm³, derived from the clause value of 3.47 with an allowed deviation of +0.08/−0.32; the refractive index is 1.67–1.73, derived from the clause value of 1.720 with an allowed deviation of +0.010/−0.050. Optically it is isotropic, often an isotropic aggregate, with no birefringence. When untreated, the lustre is vitreous, and there is no pleochroism or fluorescence. In the UV-Vis spectrum, dark green material shows total absorption at wavelengths up to 460 nm, while other colours show an absorption band near 463 nm; in the infrared spectrum, the characteristic bands of garnet appear in the mid-infrared fingerprint region, and OH vibrations form further characteristic bands in the functional-group region.
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
Hydrogrossular — composition (chemistry): The hydrogrossular formula is Ca3Al2 (SiO4) 3-ₓ (OH) 4ₓ, in which (OH) stands in for part of the (SiO4).
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Structure
Hydrogrossular — structure (overall): crystalline, or else a crystalline aggregate
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — structure (crystal system): cubic
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — structure (crystal habit): rhombic dodecahedra; mostly granular or massive 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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Hydrogrossular — 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
- General note
- hardness only, not durability
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — cleavage: none
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Physical properties
Hydrogrossular — density: 3.15–3.55 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 3.47, with a stated tolerance of +0.08 / -0.32. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Hydrogrossular — optic character: isotropic, usually as an isotropic aggregate
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — refractive index: 1.67–1.73
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.720, with a stated tolerance of +0.010 / -0.050. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — birefringence: none
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — pleochroism: none
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — fluorescence (overall): none
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — spectrum (UV-visible): dark green: 460 nm full absorption below; other colours: approximately 463 nm absorption band.
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — spectrum (infrared): Garnet's diagnostic bands show in the mid-IR fingerprint region, while OH vibration contributes further diagnostic bands to the functional-group region.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-22
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.23 (locator checked 2026-09-22)
- Fact checked on
- 2026-09-22
Hydrogrossular — magnification: mineral inclusions, aggregate of granular structure
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): §5.2.23 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Hydrogrossular — body colour: green to blue-green, pink, white, colorless, 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 Pectolite, Amblygonite, Smithsonite 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): §5.2.23 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Quality factors
Hydrogrossular — 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): §5.2.23 (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): 1.7 / 3.35; Closest values: 1Vesuvianite / Idocrase 1.711 / 3.38, 2Enstatite 1.712 / 3.31, 3Tanzanite 1.696 / 3.28, 4Fei Cui / Jadeite Jade 1.683 / 3.35, 5Axinite 1.683 / 3.31
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 registered instrument-based identification lead for Hydrogrossular is that it appears pink to red through a Chelsea colour filter, for the untreated state. This conclusion is cited from GB/T 16553—2017 Gems — Testing.
How far testing can go
Hydrogrossular — how far testing can go (instrumental testing): appears pink to red under the Chelsea colour filter
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): §5.2.23 (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.
Clause-level definitions
Hydrogrossular has a clause-level definition in GB/T 16552—2017 Annex A, Table A.2, under the entry name Hydrogrossular, defined as a garnet-series material; the cross-check result is that it is listed directly by GB/T, and CIBJO carries no standalone entry under the name Hydrogrossular.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Hydrogrossular | GB/T 16552-2017 Annex A | Hydrogrossular garnet-series material | Listed directly by GB/T; CIBJO carries no standalone entry under the same name. |
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.
Related-entry tree for Garnet on this site: 10 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Hydrogrossular) is marked.
- Garnet
Sub-entries (9)
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Garnet-group minerals and gem varieties | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Hydrogrossular 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.