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
Kornerupine
A rare silicate mineral species listed in GB/T 16552-2017 Annex A.1. For everyday wear, its cleavage and hardness should be assessed. 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 Kornerupine forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify KornerupineHow far lab testing can go and whether a synthetic exists
- Caring for and wearing KornerupineCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of KornerupineEach value with its source and check date
- Kornerupine 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 KornerupineThe listing name to use; what must be disclosed before sale
- Standard clauses that define KornerupineWhich 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
Kornerupine is listed in the CIBJO Blue Book as an independent gem material in its own right, marked as normally requiring no treatment, and confirmed as a standard material entry in the index. However, no dedicated authoritative source on kornerupine has been found (the cited sources include neither a Handbook of Mineralogy entry nor a dedicated GIA article), so its chemical composition, crystal system and specific formation mechanism cannot be confirmed from the cited sources. This entry states only the sourced identity and treatment boundaries, and flags the formation details as a gap.
Scope: Covers the description of the identity and treatment status of kornerupine as an independent material name according to the CIBJO Blue Book; does not apply to assertions about its chemical composition or formation mechanism.
Sources CIBJO Gemstone Book 2022
Where it forms
The available sources do not state an occurrence environment (host rock or tectonic setting) for kornerupine; this gap is recorded.
Sources CIBJO Gemstone Book 2022
How it forms, step by step
Kornerupine rough crystallizes in nature, but the available authoritative sources provide no description of its specific formation mechanism.
Sources CIBJO Gemstone Book 2022
As a gem material, kornerupine is normally used without treatment (CIBJO lists it as 'No treatment (Always)').
Sources CIBJO Gemstone Book 2022
Because no dedicated source is available, its chemical composition, crystal system and mode of occurrence cannot be confirmed in this record.
Sources CIBJO Gemstone Book 2022
Link to appearance
The available sources do not describe kornerupine's appearance; its color and luster must be supplemented from other authoritative mineralogical references.
Sources CIBJO Gemstone Book 2022
Timescale
The sources state no timescale for kornerupine formation.
Sources CIBJO Gemstone Book 2022
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Itrongahy, near Betroka, MadagascarListed as a source of gem crystals; other Madagascar localities exist
Sources Handbook of Mineralogy
- Mautia Hill, Kongwa, Dodoma Region, TanzaniaWell-studied specimen locality; not stated as gem-grade
Sources Handbook of Mineralogy · Mindat: Kornerupine
Asia
- Gem gravels of Matale, Ratnapura and Embilipitiya, Sri LankaGem gravels
Sources Handbook of Mineralogy · Mindat: Kornerupine
- Mogok area, MyanmarListed in the Mindat locality table; not stated as gem-grade
Sources Mindat: Kornerupine
North America
- Fiskenæsset Old Harbour, Qeqertarsuatsiaat area, Nuuk, Greenland
Sources Mindat: Kornerupine · 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.
Other research findings
Kornerupine is listed in the CIBJO Blue Book as an independent gem material in its own right, and its standard entry notes that it normally requires no treatment.
Evidence grade BScope: Applies to kornerupine's status as an independent material name; it makes no claim about its composition or origin.
Sources CIBJO Gemstone Book 2022
The available sources provide no description of kornerupine's chemical composition, crystal system or formation mechanism, so its origin cannot be determined from them.
Evidence grade CScope: States an evidence gap; it is not a formation conclusion.
Sources CIBJO Gemstone Book 2022
The CIBJO index confirms kornerupine as a standard material entry (main text page 62).
Evidence grade BScope: Only confirms it as a standard-listed material; provides no origin information.
Sources CIBJO Gemstone Book 2022
Limits of this research
- Research status: Only partial material-specific findings found; gaps are stated as gaps
- No dedicated source on kornerupine has been found (the cited sources include neither a Handbook of Mineralogy entry nor a dedicated GIA article); composition, crystal system and origin all remain gaps.
- Neither the formation environment nor the timescale is sourced; both are flagged as gaps.
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
- Kornerupine
GB/T 16552—2017 Table A.1 “Kornerupine” · IMA Mineral List 2026-07 “Kornerupine”
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
Kornerupine is Kornerupine; use "Kornerupine" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.1, row 柱晶石 (Kornerupine)
What this means for you
Before buying, check the recommended listing name "Kornerupine" 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.
Care
Kornerupine — care (cleaning): Some stones are susceptible to damage from ultrasonic cleaning. Do not expose them to ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code j
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Kornerupine, p.60; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Kornerupine — care (wear): low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code a, special-care code b
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Kornerupine, p.60; §6.2 a, b (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
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
The care conclusions for Kornerupine come from the entry listed as Kornerupine in the CIBJO Blue Book (Official Gemstone Book, 2022): registered as applying regardless of treatment status, Kornerupine should not be cleaned ultrasonically; from the same source, also regardless of treatment status, Kornerupine is soft and scratches easily, so wear it with care; Kornerupine is prone to breaking, so wear it with care.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Wearing limits (knocks, settings) | low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care |
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesThe GB/T 16552—2017 formal name for Kornerupine is set out in Table A.1; the mineralogical name is Kornerupine, and the suggested listing name is Kornerupine. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Kornerupine) and Japanese. Institution usageOn authority wording, CIBJO has Kornerupine on record (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 record show the entry's own English name, which does not represent their position. Japanese namesThe GSJ (Japan) wording for the entry's own Japanese name is not yet verified by this site.
- GSJ (Japan) formal name
- コーネルピン／コルネルプ石 (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 柱晶石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Kornerupine
Four-language names
- 简体中文
- 柱晶石
- 繁體中文
- 柱晶石
- English
- Kornerupine
- 日本語
- コーネルピン／コルネルプ石
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
Kornerupine has the chemical composition Mg3Al6(Si,Al,B)5O21(OH), and its phase is kornerupine; it is crystalline, orthorhombic, with a prismatic crystal habit. Mohs hardness is 6–7, with perfect cleavage in two directions; this site notes that hardness alone is not enough to judge durability. Density is 3.27–3.35 g/cm³; the cited clause gives 3.30 with tolerance +0.05/−0.03, from which the limits shown are derived. Optic character is anisotropic, biaxial, negative, and a pseudo-uniaxial interference figure may appear; birefringence 0.012–0.017; refractive index 1.664–1.683, the cited clause giving 1.667–1.680 with tolerance ±0.003, from which the limits shown are derived. Transparency is transparent to translucent; untreated Kornerupine has vitreous lustre. Body colour is yellowish green to brownish green, bluish green, yellow or brown, rarely colourless, for the untreated state.
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
Kornerupine — 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
Kornerupine — composition (chemistry): Mg3Al6 (Si,Al,B) 5O21 (OH)
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — composition (phase): kornerupine
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Kornerupine — 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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — structure (crystal system): orthorhombic
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — structure (crystal habit): columnar
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Kornerupine — Mohs hardness: 6–7
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — cleavage: two directions of perfect 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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Physical properties
Kornerupine — density: 3.27–3.35 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 3.30, with a stated tolerance of +0.05 / -0.03. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Kornerupine — optic character: biaxial, optically negative (anisotropic); may show an interference figure that mimics a uniaxial one.
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — refractive index: 1.664–1.683
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.667–1.680, with a stated tolerance of ±0.003. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — birefringence: 0.012–0.017
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — transparency: transparent to translucent.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Kornerupine — pleochroism: in brownish green material, strong: green, yellow and reddish brown.
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — fluorescence (overall): none to strong, yellow
GB/T 16553—2017
UV fluorescenceyellownone–strongDots 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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — spectrum (UV-visible): 503 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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — spectrum (infrared): Kornerupine's own diagnostic bands are seen 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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — optical effect (chatoyancy): seen
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — optical effect (asterism): seen; extremely rare
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Kornerupine — magnification: gas-liquid inclusions, mineral inclusions, growth striations, needle inclusions.
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): §5.1.19 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
body colour2 sources compared
Kornerupine — body colour: Yellowish to brownish green, blue-green, yellow, brown, rarely colourless.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Amblygonite, Phenakite, Chrome Tourmaline and other entries also name yellow or a yellowish colour.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Kornerupine — body colour: yellow-green through brownish green, also blue-green, yellow and brown; rarely colorless.
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 Kyanite, Barite, Amblygonite 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): §5.1.19 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
How the sources relate
- CIBJO Gemmological Laboratories Book 2024 and GB/T 16553—2017
The two entries agree: yellowish to brownish green, blue-green, yellow and brown, and both note that colourless is rare.
- CIBJO definitions
- chatoyancy, asterism
Quality factors
Kornerupine — 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): §5.1.19 (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 / 3.31; Closest values: 1Peridot 1.672 / 3.38, 2Synthetic Jadeite 1.66 / 3.34, 3Artificial Strontium Aluminate Borate 1.665 / 3.39, 4Sillimanite 1.668 / 3.21, 5Tanzanite 1.696 / 3.28
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
No synthetic counterpart of Kornerupine is commercially available. The CIBJO laboratory protocol's notes on test methods for Kornerupine are that its special optical effect is chatoyancy and that it shows a small 2V angle in the polariscope. Which tests the CIBJO laboratory protocol requires for Kornerupine, and what each method means, are in the protocol 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: §6.1.47.
How far testing can go
Kornerupine — 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
Kornerupine — notes on test methods in the CIBJO laboratory protocol:
| Test method | What the protocol notes for it |
|---|---|
| Phenomena: | Cat’s eye; |
| Polariscope: | Small 2V angle |
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- any treatment state
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Kornerupine is defined directly in the CIBJO Gemmological Laboratories Book 2024 under the entry name Kornerupine; the registered definition gives the mineral species kornerupine and IMA status G, noting that the CIBJO wording is quoted in full under Clause-level definitions on this page; cross-check result: defined directly by CIBJO; also present in the GB/T annex. A further basis for kornerupine is its entry in the IMA list of minerals, recorded under the name Kornerupine, with the formula (Mg,Fe2+,Al,☐)10(Si,Al,B)5O21(OH,F)2 and marked G with the year 1884; it was verified by cross-checking against the RRUFF/IMA list of minerals main table, and the listed data are public-domain data.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Kornerupine | 7.2.1.123 | Yellowish to brownish green, blue-green, yellow, brown, rarely colourless; transparent to translucent | Defined directly by CIBJO; also present in the GB/T annex. |
| Kornerupine | IMA Mineral List entry | Kornerupine (Mg,Fe2+,Al,☐)10(Si,Al,B)5O21(OH,F)2 G 1884 | 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.
This table scrolls sideways on narrow screens.
| 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 Kornerupine 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.