On this page
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
Black Moonstone
A market name for dark feldspar sold for a moonstone-like effect; it has no unified mineralogical definition and cannot be assumed to be moonstone. 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 Black Moonstone forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- Treatments and enhancements of Black MoonstoneThe enhancements and treatments the GB/T and JJA/AGL tables list
- Hardness, density and refractive index of Black MoonstoneEach value with its source and check date
- Black Moonstone 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 Black MoonstoneThe listing name to use; what must be disclosed before sale
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
‘Black moonstone’ is a market/trade name for dark-bodied (black, dark grey, dark brown) feldspar that shows a moonstone-like sheen; it is not a mineral species and has no authoritative mineralogical definition. The natural material is usually a dark iridescent feldspar, e.g. nearly black labradorite, or the iridescent anorthoclase in larvikite that is often misidentified as labradorite. Its darkness comes from a high density of iron oxide inclusions; because light cannot penetrate deeply, the iridescence of such material tends to be concentrated near the surface. As with all iridescent feldspars, the sheen is a structural colour from exsolution lamellae rather than a pigment colour. GIA notes that the name ‘moonstone’ has been haphazardly applied to light-coloured and other feldspars, and that darker iridescent feldspar is often misidentified on colour, so ‘black moonstone’ is a confused trade name.
Scope: Covers the natural identity and optical-effect mechanism of the dark feldspars traded as "black moonstone"; the name is a market term, and the specific mineral identity should be determined piece by piece (it may be labradorite, anorthoclase, etc.).
Sources G&G Summer 2025
Where it forms
Dark feldspar with dense iron oxide inclusions in plutonic/igneous rocks (e.g. nearly black labradorite).
Sources G&G Summer 2025
Larvikite's iridescent anorthoclase, darker in body colour and frequently mistaken for labradorite.
Sources G&G Summer 2025
How it forms, step by step
The feldspar cools slowly in a plutonic rock and exsolves into submicron lamellar textures (exsolution lamellae).
The crystal also carries a high density of iron oxide inclusions, darkening the bodycolour (black, dark grey, dark brown).
White light interferes at the exsolution lamellae to produce the structural-colour sheen, but with a dark body the light cannot penetrate deeply, so the sheen is concentrated near the surface.
The dark iridescent feldspar is marketed as ‘black moonstone’; its mineral identity (labradorite, anorthoclase, etc.) requires separate testing.
Link to appearance
The dark body and near-surface sheen are its features; bodycolour darkness is set by iron oxide inclusion density and makes the sheen appear concentrated at the surface.
Sources G&G Summer 2025
Timescale
The sources give no age or duration for the exsolution texture or iron oxide inclusions of dark feldspar.
Sources G&G Summer 2025
Related base materials
- Feldspar group: Black moonstone is a market name under which dark feldspars (such as dark labradorite or anorthoclase in larvikite) are marketed for their moonstone effect
Causes of colour and optical effects
How dark an iridescent feldspar looks is governed chiefly by how densely iron oxide inclusions are packed; this density also decides whether the iridescence shows at the surface or arises from deeper within, and dark material tends to display its sheen close to the surface.
Evidence grade AScope: A qualitative relation illustrated by labradorite; it can vary within a single crystal.
Adularescence originates in exsolution layering within alkali feldspar: on cooling, orthoclase and albite unmix into interleaved microscopic sheets stacked one above another; when the sheet spacing falls near visible wavelengths, light entering between them interferes and scatters, giving a soft blue sheen that drifts as the viewing angle changes. In darker varieties this sheen is largely confined to the near-surface zone.
Evidence grade AScope: Describes the physical mechanism of the effect; the details and provenance of the layered exsolution texture vary between samples, and the explanation does not establish the origin, naturalness, or treatment (e.g., filling) of any particular stone.
Sources GIA Moonstone Description · G&G Summer 2025
Other research findings
‘Black moonstone’ is a market/trade name for dark-bodied feldspar showing a moonstone-like sheen; authorities do not define it, and strictly a moonstone is an alkali feldspar with cryptoperthite texture.
Evidence grade AScope: Defined as a market name; its mineral identity should be tested case by case.
GIA notes the name ‘moonstone’ has been haphazardly applied to light-coloured and variously coloured feldspars, adding confusion; bodycolour is not diagnostic.
Evidence grade AScope: Terminology critique; the trade still uses moonstone-type names widely.
The iridescent anorthoclase in larvikite is darker in bodycolour and is often misidentified as labradorite due to colour — i.e. the mineral identity of dark iridescent feldspar is easily misjudged.
Evidence grade AScope: Illustrated by Norwegian larvikite (traded as ‘blue pearl’); does not imply all ‘black moonstone’ is anorthoclase.
Limits of this research
- Research status: Only partial material-specific findings found; gaps are stated as gaps
- The term ‘black moonstone’ does not appear in the authority text; this record generalises cautiously from its account of dark iridescent feldspar and confusing ‘moonstone’ naming.
- No mineral identification of individual market ‘black moonstone’ pieces is provided; no dating of inclusions or exsolution textures is given.
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
- Dark feldspar (with adularescence)
GB/T 16552—2017 5.1.1 c)
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Filled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (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
"Black Moonstone" is a market name rather than a mineral species name; before using it, verify: Trade name rather than a mineralogical species name.
What this means for you
Before buying, check the recommended listing name "Dark feldspar (with adularescence)" 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
- Trade name rather than a mineralogical species name.
- Suggested listing name
- Dark feldspar (with adularescence)
Care and wear
No care facts are recorded for this entry itself. Its parent material has care records: see Feldspar.
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 |
|---|---|---|---|---|---|
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Coating | — | — | Treatment | — | — |
| Diffusion | — | — | Treatment | — | — |
| Irradiation | — | — | Treatment | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Feldspar)
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
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Black Moonstone, the name register records "Black moonstone", for which no restriction on use as a name is recorded.
Trade and mineralogical namesBlack Moonstone is a trade name and an ambiguous market name; its identity tier is colour/appearance variety, and its mineralogical description is dark feldspar sold for a moonstone-like effect, with no unified mineralogical definition, so it cannot be assumed to be moonstone. Standard and listing namesGB/T 16552—2017 does not list Black Moonstone; the corresponding basic name in Table A.1 is feldspar, and the suggested listing name is black feldspar (moonstone effect). Under the trade-name rule of GB/T 16552—2017, a trade name is not used on its own; labelling gives the material's basic name with the trade name noted. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Black Moonstone) and Japanese; the English market name is written Black moonstone. The GSJ (Japan) wording for the entry's own Japanese name is not yet verified by this site. Institution usageAmong GIA, FTC, CIBJO and Gem-A, the FTC and CIBJO texts have no wording for Black Moonstone (checked), and GIA and Gem-A are unchecked; for bodies with no wording or not yet checked, the Black Moonstone shown is the entry's own English name and 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.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| Black moonstoneEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- ブラックムーンストーン (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)
- 长石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Dark feldspar marketed for moonstone-like sheen
Four-language names
- 简体中文
- 黑月光石
- 繁體中文
- 黑月光石
- English
- Black Moonstone
- 日本語
- ブラックムーンストーン
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Feldspar materials
- Identity tier
- Trade name: colour / appearance variety
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
In the national standard GB/T 16552—2017 Annex B, Table B.1, Black Moonstone is assigned the Feldspar entry: filling is graded, with the grade notes on this site's Gem treatments page; coating, diffusion and irradiation are all listed as treatments. The notes to Table B.1 are on this site's Gem treatments page, and the full entry with the effect column is on this site's Feldspar page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Feldspar” row of Table B.1: Filling Graded — see §5.4.1, Table 1; Coating Treatment; Diffusion Treatment; Irradiation Treatment. The full row, with the effect column, is on the Feldspar 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
For Black Moonstone, the chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are registered under feldspar (the whole mineral group); see the Feldspar entry. The other values are taken from feldspar (the whole mineral group) based on GB/T 16553—2017, not measured on Black Moonstone on its own: the structure is crystalline; the crystal system is monoclinic or triclinic for moonstone and amazonite, and triclinic for both labradorite and sunstone; crystal habit tabular or short prismatic, with Carlsbad, polysynthetic and cross-hatched (grid) twinning common; Mohs hardness 6–6.5; two directions of perfect cleavage; density 2.55–2.75 g/cm³; optical character anisotropic, biaxial, positive or negative; refractive index 1.508–1.572, birefringence 0.005–0.01; untreated, pleochroism is usually absent; iridescence, chatoyancy, asterism and aventurescence are all visible optical effects; untreated, the lustre is vitreous. The finer bands and overall values for density, refractive index and birefringence are a site note: the clause has finer bands, and the overall range is registered.
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 feldspar (the whole mineral group), so they are not repeated on the Black Moonstone page; see the material facts on the Feldspar entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Black Moonstone (how to read class-level values).
Structure
Black Moonstone — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — structure (crystal system): Moonstone and amazonite belong to the monoclinic or triclinic system; sunstone and labradorite are triclinic.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — structure (crystal habit): Crystals are tabular or stubby prisms; Carlsbad, polysynthetic and gridiron (cross-hatched) twinning are common.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Black Moonstone — Mohs hardness: 6–6.5
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
- feldspar (the whole mineral group)
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Black Moonstone — cleavage: two directions of perfect cleavage
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Black Moonstone — density: 2.55–2.75 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Black Moonstone — optic character: biaxial and anisotropic; optic sign may be either positive or negative.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — refractive index: 1.508–1.572
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Black Moonstone — birefringence: 0.005–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Black Moonstone — pleochroism: usually absent
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — optical effect (iridescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — optical effect (asterism): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Black Moonstone — optical effect (aventurescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, asterism, aventurescence
Quality factors
Black Moonstone — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (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): 1.54 / 2.65; Closest values: 1Charoite 1.554 / 2.66, 2Changhua Stone 1.56 / 2.6, 3Shoushan Stone 1.56 / 2.7, 4Balin Stone 1.56 / 2.55, 5Bamboo Coral 1.57 / 2.65
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
Evidence and sources
Authority basis and clause sources
Sources
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 Feldspar on this site: 13 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Black Moonstone) is marked.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Feldspar materials | Live |
| Treatments recorded for this material | Filled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Black Moonstone 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. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.