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Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown

Moonstone

Also known asAdularia · rainbow moonstone (conditional name)

Feldspar showing the moonstone (adularescence) effect; classic material is an orthoclase-albite intergrowth. Its GB/T basic name is "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.

Edited by JuneReviewed by RalphLast updated 2026-10-12Who maintains this page

FAQCare and wear

Questions people ask about Moonstone

Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.

Q1How can you tell if a moonstone is real?

Genuine moonstone shows adularescence, a glow that seems to billow across the stone, produced by light falling between thin, flat layers inside it.GIA Moonstone Description · G&G Summer 2025Its refractive index is recorded as 1.508–1.536.GB/T 16553—2017Its density is recorded as 2.55–2.61 g/cm³.GB/T 16553—2017Imitations exist: GIA's laboratory has examined imitation rainbow moonstones assembled from a rock crystal quartz base with an iridescent coating and a gypsum top, all coated in plastic.G&G Fall 2013Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer

Q2Is rainbow moonstone really moonstone?

Not strictly: what the trade sells as rainbow moonstone is actually labradorite, while moonstone in the strict sense is cryptoperthite.GIA Moonstone Description · G&G Summer 2025Classic moonstone is made of two feldspars, orthoclase and albite, which separate into alternating stacked layers as the newly formed mineral cools.GIA Moonstone Description · G&G Summer 2025

Q3What causes moonstone's blue or white glow?

The glow is interference of light in very thin layers: alternating albite and orthoclase lamellae typically give a blue sheen, while thin albite films in potassium-rich compositions give a bright white sheen.G&G Summer 2025It is a common misconception that the sheen comes from Rayleigh or Mie scattering; the actual mechanism is interference of light reflected by the lamellae.G&G Summer 2025

Q4Can you wear a moonstone ring every day?

Moonstone is usually set in pendants, earrings and pins rather than rings, because rings take more knocks.GIA Gem Encyclopedia (care guide)It is Mohs 6 to 6.5 with poor toughness and two cleavage directions, so a hard blow can break it.GIA Gem Encyclopedia (care guide)In settings, prong and bezel call for caution, and flush, channel and pavé for extreme caution.Gems & Gemology 1987 (Martin)

Q5How do you clean moonstone, and can it get wet?

Warm soapy water is the only recommended way to clean moonstone, and steam cleaners are never advised.GIA Gem Encyclopedia (care guide)Ultrasonic cleaning should be avoided as well, since some stones can be damaged by it.CIBJO Gemstone Book 2022High heat or a sudden temperature change can break it.GIA Gem Encyclopedia (care guide)Hydrofluoric acid harms it.GIA Gem Encyclopedia (care guide)

Q6Does moonstone fade in sunlight?

Moonstone is described as stable in light.GIA Gem Encyclopedia (care guide)For display, sunlight and artificial light are rated relatively safe, while heat inside a display case calls for caution.Gems & Gemology 1987 (Martin)

Q7Is moonstone ever treated?

Yes, according to the parent entry Feldspar: moonstone can be filled with plastic or resin to improve its transparency, and filled moonstone beads have been confirmed by infrared spectroscopy.G&G Summer 2024 · G&G Winter 2022 +1 (via parent entry Feldspar)Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer

Q8What does moonstone symbolize, and does it have healing powers?

There is no scientific evidence that moonstone has healing powers: the UK advertising regulators ASA and CAP state that they have not seen evidence that crystal therapy can treat medical conditions.ASA/CAP guidance (UK)Its recorded cultural role is as a June birthstone: Jewelers of America and Japan's JJA list it for June, and the U.K. National Association of Jewellers lists it as an alternative for June.Cultural records

Q9What makes a good-quality moonstone?

Moonstone is judged on its bodycolour and on the colour and orientation of its sheen; the most favoured stones are colourless, semitransparent to nearly transparent, free of visible inclusions and show a vivid blue sheen.GIA Moonstone Quality FactorsThe sheen should sit at the centre of the cabochon's top and show over a wide range of angles; very flat cabochons display it poorly, and tiny tension cracks called centipedes are characteristic inclusions.GIA Moonstone Quality Factors

What this page can answer

This page covers

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

  • Rough moonstone (schematic)
  • Blue-white sheen (adularescence)
  • Close-up of the gold box (schematic)
  • Orthoclase (schematic colour)
  • Albite lamellae / films (schematic colour)
  • Milky, translucent (after alteration; schematic)
How moonstone forms: a schematic animation, not to scale; the captions are taken from the research record under “Material research” on this page.

If you reuse this animation, please credit LumaLark Wiki and link to this pageLicense: CC BY 4.0

Scene-by-scene transcript (10 scenes, with evidence grades and sources)

The caption of each scene in the animation above, with its evidence grade and sources.

  1. Scene 1What moonstone is

    Moonstone is made of two feldspars — orthoclase and albite — which, as the newly formed mineral cools, separate into alternating stacked layers.

    Scope: Covers alkali feldspars that show adularescence produced by exsolution textures in cryptoperthite; trade names such as "rainbow moonstone" actually refer to labradorite and must be assessed separately.

    Sources
  2. Scene 2Where the constituent minerals generally occur (mineral level)

    General occurrence of the constituent minerals (mineral level, not specific to moonstone): orthoclase is the common feldspar of granites, granite pegmatites and syenites; albite is a major constituent of granites and granite pegmatites and also occurs in alkalic diorites, basalts, and hydrothermal and alpine veins.

    Alkali feldspar (orthoclase–albite) solid-solution systems; the cited sources do not specify the host-rock settings of moonstone

    Sources
  3. Scene 3Alkali feldspar crystallizes, at first as a solid solution

    Potassium- and sodium-bearing alkali feldspar crystallizes, with the orthoclase and albite components at first intermingled within one crystal (a solid solution) and not yet separated; cryptoperthite is the product of later exsolution on cooling.

    Sources
  4. Scene 4At the atomic scale: Na⁺ and K⁺ segregate

    Cooling-induced exsolution proceeds by the segregation of Na⁺ and K⁺ on the extra-framework cation sites, while the tetrahedral framework itself stays unchanged apart from small distortions.

    Evidence grade A

    Scope: The atomic-scale mechanism of alkali-feldspar exsolution, not specific to any locality.

    Sources
  5. Scene 5On cooling, the solid solution decomposes

    On cooling the solid solution decomposes: intermediate compositions exsolve by spinodal decomposition into alternating lamellae, while potassic compositions nucleate and grow albite films

    Sources
  6. Scene 6Slow cooling may cause exsolution at different scales (general rule)

    Alkali feldspars of intermediate composition that are cooled slowly from high temperatures may unmix, or exsolve, to form perthite, an intergrowth of orthoclase (or microcline) and albite; microperthite and cryptoperthite are perthites whose exsolution features are microscopic and submicroscopic in scale, respectively.

    Evidence grade B

    Scope: A general rule of alkali-feldspar exsolution (university lecture notes, rated B); moonstone in the strict sense is cryptoperthite, and this entry gives no specific temperature or cooling rate for its formation.

    Sources
  7. Scene 7The exsolution texture may coarsen (general rule)

    During isothermal annealing or slow cooling, the exsolution texture may coarsen to reduce interface area, leading to micro- or even macro-perthite.

    Evidence grade B

    Scope: A general rule for alkali-feldspar exsolution textures (university lecture notes, rated B), not specific to any locality.

    Sources
  8. Scene 8Low-temperature fluid alteration

    Low-temperature fluid alteration: strained lamellar interfaces are vulnerable to it, which is why moonstone is almost always milky and translucent, with the sheen appearing shallow beneath the surface

    Sources
  9. Scene 9Light interferes between the layers

    Interference of light reflected by the lamellae yields a blue-white glow that shifts with the viewing angle — adularescence

    It is a common misconception that moonstone's sheen arises from Rayleigh or Mie scattering; the actual mechanism is interference of light reflected by lamellae.

    Evidence grade A
    Sources
  10. Scene 10What you end up seeing

    Moonstone's sheen is structural color from lamellar interference over a milky bodycolor

    Timescale: The sources give no absolute time span for moonstone exsolution, only the decomposition and coarsening sequence during cooling.

    Sources

In brief: Moonstone's formation/light mechanism centers on exsolution texture in alkali feldspar and the interference of light.

Full research record (formation summary, 4 formation steps, link to appearance, related base materials, 1 supporting finding)

Moonstone's formation/light mechanism centers on exsolution texture in alkali feldspar and the interference of light. As the orthoclase–albite system cools, the solid solution decomposes: intermediate compositions (~Ab80Or20–Ab40Or60) first undergo spinodal decomposition into alternating albite/orthoclase lamellae with interfaces nearly parallel to the (6̄01) plane, while more potassic compositions exsolve albite films by nucleation and growth; the lens-shaped albite films, thicker in the middle and tapering at the edges, vary continuously in thickness from zero to a few hundred nanometers. White light interferes between these films (thin-film interference), producing the soft blue-white sheen gemology calls adularescence. Because the strained lamellar interfaces are vulnerable to low-temperature fluid alteration, moonstone is almost always milky and translucent, with the sheen appearing shallow beneath the surface and shifting with the viewing angle.

Sources G&G Summer 2025 · GIA Moonstone Description
How it forms, step by step

  1. Potassium- and sodium-bearing alkali feldspar crystallizes, with the orthoclase and albite components at first intermingled within one crystal (a solid solution) and not yet separated; cryptoperthite is the product of later exsolution on cooling.

    Sources GIA Moonstone Description · G&G Summer 2025

  2. On cooling the solid solution decomposes: intermediate compositions exsolve by spinodal decomposition into alternating lamellae, while potassic compositions nucleate and grow albite films, with interfaces nearly parallel to (6̄01).

    Sources G&G Summer 2025 · GIA Moonstone Description

  3. White light interferes between the lamellae: alternating lamellae in intermediate compositions typically give a blue sheen, while the lens-shaped albite films in potassic compositions vary continuously in thickness from zero to a few hundred nanometers, so thin-film interference spans the whole visible spectrum and gives a bright white sheen.

    Sources G&G Summer 2025 · GIA Moonstone Description

  4. Interference of light reflected by the lamellae yields a blue-white glow that shifts with the viewing angle — adularescence; low-temperature fluid alteration makes moonstone almost always milky and translucent, so the sheen appears shallow beneath the surface.

    Sources G&G Summer 2025 · GIA Moonstone Description
Link to appearance

Moonstone's sheen is structural color from lamellar interference over a milky bodycolor; bodycolour depends mostly on inclusion type and density, while the sheen colour relates to the lamellar texture (exsolution path and lamellar thickness).

Sources G&G Summer 2025
Related base materials
  • Orthoclase–albite intergrowth (cryptoperthite): The principal mineral assemblage of classic moonstone
  • Labradorite: The 'rainbow moonstone' on the market is actually labradorite, not orthoclase moonstone
  • Sanidine: Some sanidine can also show the moonstone effect and is called moonstone
Supporting findings

Moonstone is made of two feldspars — orthoclase and albite — which, as the newly formed mineral cools, separate into alternating stacked layers.

Evidence grade A

Scope: A GIA descriptive account; cooling is described qualitatively, not as a dated history.

Sources GIA Moonstone Description · G&G Summer 2025

Recorded localities

Authoritative sources list the localities below; the list is not exhaustive.

Locality sketch mapLand outlines only; the map does not depict any national or regional boundary. Dots mark approximate positions. Base map: Natural Earth (public domain).

Africa

Asia

North America

South America

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

Light falling between the thin, flat layers inside moonstone produces adularescence — a glow that appears to billow across the gem.

Evidence grade A

Scope: The encyclopedia says 'scatters'; the G&G review refines the mechanism to thin-film interference.

Sources GIA Moonstone Description · G&G Summer 2025

In intermediate alkali feldspars, spinodal decomposition forms alternating albite/orthoclase lamellae (interfaces nearly parallel to (6̄01)), and such moonstones typically show a blue sheen of varying saturation; the albite films exsolved in potassic compositions give a bright white sheen through thin-film interference.

Evidence grade A

Scope: The two exsolution paths differ: spinodal lamellae in intermediate compositions typically give a blue sheen (occasionally light yellow), while albite films of continuously varying thickness in potassic compositions give a bright white sheen; the source notes that direct correlations between textures and sheen colours have not been carefully investigated, so sheen colour alone should not be used to infer the exsolution path.

Sources G&G Summer 2025

It is a common misconception that moonstone's sheen arises from Rayleigh or Mie scattering; the actual mechanism is interference of light reflected by lamellae.

Evidence grade A

Scope: The clarification concerns moonstone in general: the milky look stems from low-temperature fluid alteration and is not the cause of the sheen; appearance varies with alteration.

Sources G&G Summer 2025

Human use and museum objects

The earliest object recorded as 'moonstone' is the Cleveland Museum of Art's ancient Greek necklace (1928.234, 100s BCE); The Met's Chinese Song-dynasty ornament (26.191.9, 960–1279) is also labelled 'moonstone'. The evidence is dominated by late-19th- to 20th-century jewellery; 'moonstone' is a trade/usage name for a feldspar-group gem variety, not an independent mineral species (its parent material is feldspar).

Evidence grade A

Scope: Based only on the museum's cataloguing of these specific objects; it is not generalized to widespread practice or universal use of the material.

Sources Cleveland Museum of Art 1928.234 · The Met 26.191.9 · The Met 53.153.7 +3

Moonstone is not an independent mineral species but a gem variety of the feldspar group (orthoclase–albite intergrowth, cryptoperthite); where collection records say 'moonstone' they refer to that feldspar material. Museum evidence is mostly modern jewellery: the Cleveland Museum of Art's ancient Greek necklace (1928.234, 100s BCE) includes 'moonstone' in its medium — the earliest instance — and The Met's Chinese Song-dynasty ornament (26.191.9, 960–1279) is 'Gold, moonstone'; the remainder are chiefly late-19th- to 20th-century Western jewels, e.g. Met 53.153.7 'Necklace with Pendant' (ca. 1910, 'Moonstones, sapphires, platinum'), Met 1998.356 brooch (ca. 1912–13, 'Gold, enamel, moonstones'), Met 2016.630 necklace (ca. 1915, 'Gold, sapphires, and moonstones') and Cleveland 1944.73 ring (1800s, 'gold with moonstone and rubies', Cambodia). Note that Met 2009.300.3249a, b is titled 'The Moonstone' but is made of silk and is not moonstone material.

Sources Cleveland Museum of Art 1928.234 · The Met 26.191.9 · The Met 53.153.7 +3

Scope: A museum object evidences only that artefact's existence and date; it does not establish widespread ancient use of the material, nor does it authenticate the origin, naturalness or treatment of any modern specimen.

Objects cited

500 BCE0500100015002000CMA 1928.234100s BCECMA 1944.731800sMet 53.153.7ca. 1910Met 1998.356ca. 1912–13Met 2016.630ca. 1915
Dates of museum objectsDates from the museums' open-access records (CC0); each bar spans the whole period named in the record, with qualifiers such as “early” or “possibly” kept in the label rather than turned into a narrower range; an arrow marks a record that reads “before” or “after” a yearSource: The Met / Cleveland Museum of Art open-access records

Cultural records for this material: Birthstone list.

How it is identified

Imitations of rainbow moonstone are on record: GIA's laboratory examined assembled cabochons made of a natural rock crystal quartz base carrying an iridescent coating, cemented to a gypsum top, with the whole piece coated in colourless plastic; gas bubbles in the cement layer gave them away as assemblages.

Evidence grade A

Scope: Limited to the assembled stones described in that laboratory report; it is not a list of every moonstone imitation and not a method for readers to identify stones themselves.

Sources G&G Fall 2013

Other research findings

Strictly, moonstone is cryptoperthite; trade 'rainbow moonstone' is actually labradorite, and sanidine may also be adularescent.

Evidence grade A

Scope: A gemological naming convention; in the trade the name moonstone is used loosely.

Sources GIA Moonstone Description · G&G Summer 2025

Moonstone is judged on three key factors: its bodycolour and the colour and orientation of its sheen. The most favoured stones are colourless and semitransparent to nearly transparent, show no visible inclusions and have a vivid blue sheen.

Evidence grade B

Scope: Quality factors as described by one educational source; not a grading standard and not a statement about the value of any piece.

Sources GIA Moonstone Quality Factors

The sheen should sit at the centre of the cabochon's top and be visible over a wide range of viewing angles; if it only shows within a narrow range its value drops, and very flat cabochons display the sheen poorly. Tiny tension cracks known as centipedes are characteristic inclusions.

Evidence grade B

Scope: Cutting and appearance factors as described by one educational source; not a grading standard.

Sources GIA Moonstone Quality Factors

Limits of this research

  • Research status: Formation, occurrence or other material-specific findings found in authoritative sources
  • The GIA encyclopedia page describes the effect as 'scattering'; the G&G review states that attributing the sheen to Rayleigh or Mie scattering is a misconception and that the mechanism is interference of light reflected by lamellae (it also discusses reflection and scattering at the lamellar interfaces). This record follows the G&G interference account while preserving the GIA wording.
  • Moonstone is a trade/variety name whose actual mineral identity may be orthoclase, sanidine or labradorite (rainbow moonstone) and must be determined mineralogically.

Methodology

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
Moonstone

GB/T 16552—2017 Table A.1 “Moonstone” · CIBJO Gemmological Laboratories Book 2024 §7.2.1.150

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

"Moonstone" is a market name rather than a mineral species name; before using it, verify: Industry-wide term that does not denote a single species.

What this means for you

Before buying, check the recommended listing name "Moonstone" 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

Trade-name ruling

  • Industry-wide term that does not denote a single species.
Suggested listing name
Moonstone

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

care (cleaning)3 sources compared

Moonstone — care (cleaning): Warm soapy water is the only recommended cleaner; steam cleaners are never advised either.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — 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
Fact checked on
2026-09-25

Moonstone — care (cleaning): ultrasonic and steamer: avoid; note: avoid heat.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — care (heat): High heat or a sudden temperature change can break it

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — care (chemicals): stable in light, but hydrofluoric acid harms it.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

care (wear)2 sources compared

Moonstone — care (wear): Mohs 6 to 6.5 with poor toughness and two cleavage directions, so a hard blow can break it.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — care (wear): 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 b

Treatment state
any treatment state
Source & check 2026-09-25
Source
Fact checked on
2026-09-25

Moonstone — care (special care): normal care

AGTA Gemstone Information Manual, 17th ed.

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

care (setting)2 sources compared

Moonstone — care (setting): Makers therefore usually set it in pendants, earrings and pins rather than rings, which take more knocks.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — care (setting): prong and bezel: use caution; flush, channel and pavé: use extreme caution; note: perfect, easy cleavage in two directions.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — care (repair): polishing: use extreme caution; jeweller's torch, pickle pot and thermal shock: avoid; note: avoid heat, which may crack or cleave it.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — care (display): sunlight and artificial light: relatively safe; heat in the display case: use caution.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
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.

Common care questions and matching entries

Each question links to the matching entries on this page; whether they answer it fully, go by the entry wording.

This table scrolls sideways on narrow screens.

QuestionMatching entries
Can it go in an ultrasonic or steam cleaner?Warm soapy water is the only recommended cleaner; steam cleaners are never advised either; care (cleaning); ultrasonic and steamer: avoid; note: avoid heat
Heat and thermal shockHigh heat or a sudden temperature change can break it; polishing: use extreme caution; jeweller's torch, pickle pot and thermal shock: avoid; note: avoid heat, which may crack or cleave it
Light and displaysunlight and artificial light: relatively safe; heat in the display case: use caution
Contact with acids, alkalis and household chemicalsstable in light, but hydrofluoric acid harms it
Wearing limits (knocks, settings)Mohs 6 to 6.5 with poor toughness and two cleavage directions, so a hard blow can break it; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care; Makers therefore usually set it in pendants, earrings and pins rather than rings, which take more knocks; prong and bezel: use caution; flush, channel and pavé: use extreme caution; note: perfect, easy cleavage in two directions

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

untreated

Durability and wearing

Toughness

Poor

Sources GIA Gem Encyclopedia (care guide)

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.

TreatmentMarket frequency (CIBJO)Stability (CIBJO)GB/T 16552 categoryJJA/AGL listingIdentification 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); JJA/AGL 2025

Whether a treatment has to show in the name differs between the two rule sets (this site’s paraphrase):

  • GB/T 16552—2017: a method classed as treatment has to be stated in the name itself — the method put before the name, or added in brackets after it; a method classed as optimization does not need to appear in the name, though one marked “Optimization (annotation required)” still has to be noted in the quality documents. Source: §5.4.2.1 a), b); §5.4.2.2 a)
  • CIBJO Gemstone Book 2022: no longer splits treatments into ones that need specific disclosure and ones that need only general disclosure: every treatment is to be disclosed, and the seller tells the buyer which treatment was used and what special care it calls for. Source: §4.2.5 Note 2, §4.2.5.1, pp.14–15

What this table covers

What this page can give

  • Registered treatments, their stability and how often they occur (see the table above)
  • Identification leads for each treatment, for use when sending a stone for testing

VerifyNames, standards, technical facts, clauses and sources

Names

Besides Moonstone, the name register records "Adularia" and "rainbow moonstone", for which no restriction on use as a name is recorded; 2 further names in non-Latin scripts are listed in the name register below (2 with no restriction recorded on use as a name).

Standard and listing namesThe Chinese formal name for Moonstone is based on GB/T 16552—2017 Table A.1, and the suggested listing name is Moonstone. Names in four languagesNames are given in Simplified Chinese, Traditional Chinese, English (Moonstone) and Japanese, and the GSJ (Japan) formal name is given in both katakana and the Japanese term for moonstone. Institution usageGIA and CIBJO list the wording Moonstone, CIBJO in the Gemmological Laboratories Book 2024; the FTC text contains no wording for this name (checked), and Gem-A is unchecked. National standard namesNational and regional formal names: Germany (RAL) Mondstein, the European Union Moonstone, France (DGCCRF) Pierre de lune. Mineralogically, Moonstone is a feldspar showing adularescence, classically an orthoclase–albite intergrowth, and other feldspars may also be traded as moonstone. Candidate search termsAdularia is an older name, and rainbow moonstone is a narrower name, kept as a search candidate only. Trade and mineralogical namesOrange moonstone and grey moonstone are market names with colour qualifiers; grey moonstone may be ambiguous, as grey and black moonstone are often lumped together on the market, and if the material is actually black moonstone it should map to the Black Moonstone entry.

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.

NameTypeMatchingUse as a nameBasis
no restriction recorded (4)
AdulariaEnglishhistorical namematched automaticallyno restriction recordededitorial ruling (no clause cited)
rainbow moonstoneEnglishnarrower name (variety or subtype)search candidate onlyno restriction recordededitorial ruling (no clause cited)
橙月光石Simplified Chinesemarket namematched automaticallyno restriction recordededitorial ruling (no clause cited); Note: Colour qualifier.
灰月光石Simplified Chinesemarket namematched automaticallyno restriction recordededitorial ruling (no clause cited); Note: Colour qualifier. ⚠️ Possibly ambiguous: there is a separate black moonstone entry and the market often mixes grey and black moonstone; material that is in fact black moonstone belongs to that entry.

How each authority words this name: see Names › Authority wording.

Authority wording

GIA, FTC, CIBJO, Gem-A
Moonstone (on record for GIA, CIBJO (GIA Gem Encyclopedia; CIBJO Gemmological Laboratories Book 2024 §7.2.1.150); no wording for this name in the FTC text on file; Gem-A unchecked — bodies without a recorded wording show the entry's own English name)
GSJ (Japan) formal name
ムーンストーン／月長石
Chinese formal name
月光石 (GB/T 16552—2017 Table A.1)
Mineralogical name
Adularescent feldspar; classic moonstone is orthoclase–albite intergrowth, while other feldspars may be traded as moonstone
Trade names and synonyms
Adularia (historical name) · rainbow moonstone (narrower name (variety or subtype); conditional name)

Four-language names

简体中文
月光石
繁體中文
月光石
English
Moonstone
日本語
ムーンストーン

National and regional formal names

Germany (RAL)
Mondstein
European Union
Moonstone
France (DGCCRF)
Pierre de lune

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
Mineral / gemstone variety
Mineral chemical class
Silicates
Construction or treatment status
Natural identity; treatment status unknown

Treatments listed by standards

GB/T 16552-2017, Annex B, Table B.1

Under the “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.

JJA/AGL (Japan) table of principal gem names, 2025

This table scrolls sideways on narrow screens.

Gem nameSpeciesColourListed in the tableNotes
PeristeritePeristeritewhitelisted under “Peristerite” in the table; this page is related (the source does not name it); peristerism; also called albite moonstone; no dedicated entry on this site; shown on the broader entry
MoonstoneOrthoclasewhite, greenish, orange, pink, greyan untreated tier is listedadularescence or schiller

JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.15

How to read the JJA/AGL table: see the Gem treatments page.

What it is and how it's identified

The composition (phase) of Moonstone is the feldspar group; the overall structure, per feldspar as a whole mineral group, is crystalline, in the monoclinic or triclinic system, and the habit, per the feldspar group, is tabular or short prismatic, often with Carlsbad, polysynthetic and cross-hatched twinning. Per the feldspar group, Mohs hardness is 6–6.5 and cleavage is two perfect directions. Per the feldspar group, density takes the overall value of 2.55–2.75 g/cm³; another density clause gives 2.58 with a tolerance of ±0.03, which works out to 2.55–2.61 g/cm³. Refractive index per the feldspar group takes the overall value of 1.508–1.572; another refractive index clause gives 1.518–1.526 with a tolerance of ±0.010, which works out to 1.508–1.536. Birefringence per the feldspar group takes the overall value of 0.005–0.01, with a further value of 0.005–0.008. Optical character per the feldspar group is anisotropic, biaxial positive or negative. Transparency is translucent to transparent, and the moonstone effect (adularescence) can be seen; per the feldspar group, iridescence, chatoyancy, asterism and aventurescence can be seen.

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 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 Moonstone (how to read class-level values).

Definition

Moonstone — composition (phase): feldspar group

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Structure

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

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

Moonstone — structure (crystal system): monoclinic or triclinic

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): §5.1.17 Crystal system · Moonstone, amazonite (locator checked 2026-09-28)
Fact checked on
2026-09-26

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

Moonstone — Mohs hardness: 6–6.5

GB/T 16553—2017

123456789106–6.5References (diamond = value, bar = range; below)

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))

Mohs hardnessSource: GB/T 16553—2017
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

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

Moonstone — density: 2.55–2.75 g/cm³

GB/T 16553—2017

0.51.52.53.54.55.56.57.52.55–2.75
Specific gravitySource: 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

Moonstone — density: 2.55–2.61 g/cm³

GB/T 16553—2017

0.51.52.53.54.55.56.57.52.55–2.61
Specific gravitySource: GB/T 16553—2017
Does this standard apply
applies to this entry
Qualification

The clause we cite gives 2.58, with a stated tolerance of ±0.03. The range shown here is worked out from that.

Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Density · Moonstone (locator checked 2026-09-28)
Fact checked on
2026-09-26

Optical

Optical effects on record: iridescencechatoyancyrepresentative example: cause in Tiger’s Eye (schematic)asterismrepresentative example: cause in Star Sapphire (schematic)aventurescencerepresentative example: cause in Sunstone (schematic)adularescencecause (schematic)

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

Moonstone — refractive index: 1.508–1.572

GB/T 16553—2017

1.31.72.12.52.93.31.508–1.572
Refractive indexSource: 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

Moonstone — refractive index: 1.508–1.536

GB/T 16553—2017

1.31.72.12.52.93.31.508–1.536
Refractive indexSource: GB/T 16553—2017
Does this standard apply
applies to this entry
Qualification

The clause we cite gives 1.518–1.526, with a stated tolerance of ±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): §5.1.17 Refractive index · Moonstone (locator checked 2026-09-28)
Fact checked on
2026-09-26

Moonstone — birefringence: 0.005–0.01

GB/T 16553—2017

00.050.10.150.20.250.30.005–0.01
BirefringenceSource: 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

Moonstone — birefringence: 0.005–0.008

GB/T 16553—2017

00.050.10.150.20.250.30.005–0.008
BirefringenceSource: 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): §5.1.17 Birefringence · Moonstone (locator checked 2026-09-28)
Fact checked on
2026-09-26

Moonstone — transparency: translucent to transparent.

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

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

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

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

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

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

Moonstone — optical effect (adularescence): adularescence.

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Moonstone — magnification: visible centipede-like inclusion, visible fingerprint-like inclusions, visible needle inclusions.

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Magnification (locator checked 2026-09-28)
Fact checked on
2026-09-26

body colour2 sources compared

Moonstone — body colour: a wide range of colours, such as (near-) colourless, brown, orange, yellow, grey.

CIBJO Gemmological Laboratories Book 2024

Treatment state
untreated
Qualification

In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Scheelite, Magnesite, Labradorite and other entries also name colourless.

General note
colour alone is not identity
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Moonstone — body colour: white to colourless, showing a blue, yellow or colourless moonlight-like sheen.

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 Calcite, Euclase, Dolomite and other variety clauses also name colourless.

General note
colour alone is not identity
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Colour · Moonstone (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

complementary, no conflict

Both include colourless. GB/T 16553—2017 gives the body colour (colourless to white) and the colour of the moonlight effect (blue, yellow or colourless); the CIBJO Gemmological Laboratories Book says the colours vary widely and also lists brown, orange, yellow and grey.

Light falling between the thin, flat layers inside moonstone produces adularescence — a glow that appears to billow across the gem.

Schematic of the cause of adularescence: thin, flat layers
adularescenceSchematic, not to scaleDrawn from the cause recorded under “Material research” on this page (source: GIA Moonstone Description · G&G Summer 2025)If you reuse this image, please credit LumaLark Wiki and link to this pageLicense: CC BY 4.0
CIBJO definitions
chatoyancy, asterism, aventurescence, adularescence

Quality factors

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.

1.531.541.551.561.571.582.42.52.62.72.8Refractive indexSpecific gravity12345Moonstone

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)1.41.51.61.71.81.922.12.22.32.41234567Refractive indexSpecific gravity12345Moonstone

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

Refractive index × specific gravity (all registered materials)Each dot is one material's registered refractive index and specific gravity (range midpoints, not measurements); gold = this material, dark = the nearest few (picked on this site by distance in RI ÷ 0.02 and SG ÷ 0.1, leaving out near-identical varieties of the same species)Source: each material's registered refractive index and specific gravity facts (GB/T 16553 and others; sources on each entry)

Testing and market

The CIBJO laboratory protocol covers Moonstone under “Feldspar” (§6.1.33): see identification on the Feldspar entry; the required tests are listed on the CIBJO laboratory protocol table for Feldspar.

How far testing can go

Each row's “Source & check” expands to the full source; the date beside it is the fact check date.

Clause-level definitions

Moonstone has a direct definition in the CIBJO Gemmological Laboratories Book 2024 under the term Moonstone, which describes it as a feldspar, translucent to transparent, that occurs in a broad range of colours, for example (near-) colourless and brown. The cross-check shows it is defined directly by CIBJO and also appears in the GB/T annex. The CIBJO Gemmological Laboratories Book 2024 also gives a direct definition under the term Rainbow moonstone, described as a feldspar with deep blue adularescence that is translucent to transparent; for Rainbow moonstone, the cross-check shows it is defined directly by CIBJO, and no identically named English entry was found in this edition of the GB/T annex.

This table scrolls sideways on narrow screens.

TermClauseDefinitionCross-check
Moonstone7.2.1.150Moonstone is a translucent to transparent feldspar, showing a wide range of colours, such as (near-) colourless, brown, orange, yellow, grey, and which reflects a bluish, milky sheen (adularescence) that has been compared to the light of the moonDefined directly by CIBJO; also present in the GB/T annex.
Rainbow moonstone7.2.1.191Rainbow moonstone is a translucent to transparent feldspar, showing a deep blue adularescence, or a variety of iridescent coloursDefined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex.

Evidence and sources

Authority basis and clause sources

GB/T 16552—2017
Listed Table A.1 “Moonstone” · Source
CIBJO Gemmological Laboratories Book 2024
Listed §7.2.1.150 · Source

Sources

Further reading

Related pages

Treatments recorded for this material

Recorded cultural contexts

Birthstone list

The U.S. Jewelers of America roster lists Moonstone for June; the U.K. National Association of Jewellers chart lists Moonstone as an alternative for June; and Japan's JJA 2021 revised roster lists Moonstone for June. This records trade-association convention only; it does not establish material identity, natural origin, treatment, provenance, or effect.

Relation
Industry list inclusion

This table scrolls sideways on narrow screens.

Publisher or holderRegionFrom / periodSource and locator
Jewelers of AmericaUnited States1912 to the presentJewelers of America, “Birthstone Jewelry” (web page, consulted 2026-08-22)
Birthstone roster table, June row: Moonstone
Japan Jewellery AssociationJapanfrom 20 December 2021Tanjoseki (Japanese birthstone roster, Japan Jewellery Association page; revision of 20 December 2021)
2021 revised birthstone roster, June row: Moonstone
National Association of JewellersUnited Kingdom—National Association of Jewellers, “Zodiac Birthstones Jewellery: Star Signs, Gemstones and Their Meaning” (web page, consulted 2026-08-22)
Zodiac birthstone chart, June row: Moonstone (Alternative)

Related intention themes

These reviewed links connect this material with LumaLark intention themes. Each label identifies whether the link is a brand interpretation or a historical and cultural record; neither describes an effect or outcome of the material.

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 (Moonstone) is marked.

This table scrolls sideways on narrow screens.

PageContentStatus
Browsing familyFeldspar materialsLive
Treatments recorded for this materialFilled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (via parent material)Live
Related articlesTo be added (placeholder)Planned

Who maintains this page

The material facts in the 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; 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.

Facts editor
June
Reviewer
Ralph
How facts are checked
Each fact is matched to the clause it cites; facts checked between 2026-09-21 and 2026-09-26
Last revised
2026-10-12
Purpose
Lets buyers and sellers check naming, disclosure and material facts clause by clause.

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