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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Labradorite (Spectrolite)
Labradorite showing play of colour across the full spectrum; fine material from Finland is called Spectrolite in the trade. The colour play itself is not a treatment. 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.
Questions people ask about Labradorite (Spectrolite)
Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.
Q1What is the difference between spectrolite and labradorite?
Spectrolite is a rare variety of labradorite from Finland.G&G in a Flash, Summer 2025Labradorite itself is plagioclase feldspar with a composition between An50 and An70, and labradorescence is the iridescent schiller that it can display.G&G Summer 2025
Q2What gives spectrolite its full range of colours?
As in other iridescent labradorite, the colour is structural: light interfering in the periodic Bøggild lamellae produces a highly saturated, directional colour seen on a cleavage surface.G&G Summer 2025The colour follows the total thickness of the lamellae: about 150 nm gives blue, more than 250 nm gives red, and a continuous spectrum lies in between.G&G Summer 2025Iridescent labradorite is often dark in bodycolour because of iron oxide inclusions, and that darkness affects how the iridescence appears.G&G Summer 2025
Q3What makes good-quality spectrolite?
A Gems & Gemology overview of phenomenal gems says spectrolite is highly prized for its rich, full-spectrum colours and stronger labradorescence.G&G in a Flash, Summer 2025It often shows several colours at once and is regarded as the most vivid example of the effect.G&G in a Flash, Summer 2025
Q4Is all labradorite sold as spectrolite from Finland?
GIA uses spectrolite as the trade name for labradorite from Finland, found in a small area in the country's southeast.GIA News (2016) · GIA News (2017) +1CIBJO's standards, by contrast, list spectrolite as an accepted trade name for labradorite showing labradorescence and state no required origin.CIBJO Gemstone Book 2022 · CIBJO Gemmological Laboratories Book 2024No authoritative source on record says how Finnish material can be told from labradorite of other origins sold under the name.CIBJO Gemstone Book 2022 · CIBJO Gemmological Laboratories Book 2024
Q5How should spectrolite be worn and cleaned?
CIBJO adds two special-care notes for labradorite with labradorescence: it can cleave or fracture easily, so wear it with care, and ultrasonic cleaning can damage it.CIBJO Gemstone Book 2022For the parent entry Feldspar, a CIBJO retail guide advises a clean cloth dampened with water only, with no soap or other cleaning agent, and never an ultrasonic cleaner.CIBJO Retailers' Reference Guide (2021) (via parent entry Feldspar)China's national standard gives the feldspar group a Mohs hardness of 6–6.5, a class figure rather than a measurement of spectrolite.GB/T 16553—2017The feldspar group has two directions of perfect cleavage.GB/T 16553—2017
Q6Where does spectrolite come from, and how did it form?
GIA describes spectrolite as labradorite found in a small area of southeastern Finland.GIA News (2016) · GIA News (2017) +1Iridescent labradorite in general occurs in plutonic rocks that cooled extremely slowly or underwent high-grade metamorphism.G&G Summer 2025As the plagioclase cools it can separate into thin, alternating lamellae, and these submicron textures are where labradorescence comes from.G&G Summer 2025
What this page can answer
This page covers
- How Labradorite (Spectrolite) forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- How to identify Labradorite (Spectrolite)How far lab testing can go
- Treatments and enhancements of Labradorite (Spectrolite)The enhancements and treatments the GB/T and JJA/AGL tables list
- Hardness, density and refractive index of Labradorite (Spectrolite)Each value with its source and check date
- Labradorite (Spectrolite) 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 Labradorite (Spectrolite)The 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
Iridescent labradorite is labradorite that shows labradorescence - the iridescent schiller characteristic of plagioclase feldspar labradorite from plutonic rocks. Labradorite itself is plagioclase with a composition in the An50-An70 span of the albite-anorthite continuous solid-solution series. Its colour is not due to pigment but to structure: under extremely slow cooling or high-grade metamorphism the mineral exsolves into the alternating thin layers called the Bøggild intergrowth - wider calcic lamellae (roughly 70-200 nm) and thinner sodic lamellae (roughly 50-100 nm), lying close to parallel to the (3̄202) plane - so the interference colour appears on the (010) cleavage surface. That colour tracks the total lamellae thickness: adjacent calcic and sodic lamellae totalling about 150 nm give blue, more than 250 nm gives red, and a continuous spectrum lies between. Iridescent labradorite is found in plutonic rocks that cooled extremely slowly or underwent high-grade metamorphism, with bulk compositions in the range An46±2 to An60±2, and crystals can reach several decimetres across.
Scope: Applies to the origin of labradorescence in natural labradorite (multilayer interference from Bøggild exsolution lamellae) and its occurrence; does not cover synthetic, assembled or copper-diffusion-treated material.
Sources G&G Summer 2025
Where it forms
Cooled extremely slowly or metamorphosed at high grade, plutonic rocks - frequently anorthositic - are where iridescent labradorite forms.
Sources G&G Summer 2025
A solid-solution exsolution setting (during cooling): alternating calcic and sodic lamellae exsolve to form the Bøggild intergrowth.
Sources G&G Summer 2025
How it forms, step by step
During extremely slow cooling or high-grade metamorphism, calcic plagioclase unmixes (exsolves) from the homogeneous solid solution.
The Bøggild intergrowth is built of wider calcic lamellae (roughly 70-200 nm) alternating with thinner sodic lamellae (roughly 50-100 nm), lying mostly parallel to the (3̄202) plane.
Incident light undergoes multilayer (thin-film) interference between the periodic lamellae pairs, producing an angle-dependent interference colour.
The interference colour depends on the total lamellae thickness: ~150 nm gives blue, >250 nm gives red, with a continuous spectrum in between; colour zones within one crystal correlate with composition.
Link to appearance
Iridescent labradorite's colour is structural: multilayer interference from the periodic Bøggild lamellae produces a highly saturated, directional colour seen on the (010) cleavage; the bodycolour (often dark from iron oxide inclusions) affects how the iridescence appears.
Sources G&G Summer 2025
Timescale
The sources place iridescent labradorite in plutonic rocks that cooled extremely slowly or underwent high-grade metamorphism, and they survey two centuries of work on exsolution; they give no absolute age and no duration for either the exsolution or the crystallisation.
Sources G&G Summer 2025
Related base materials
- Labradorite (plagioclase An50-70): variety-of | Spectrolite is labradorite that shows labradorescence
- Plagioclase solid-solution series (albite-anorthite): range-of | Labradorite is the An50–70 compositional range of the plagioclase solid solution
Supporting findings
Around the world, iridescent labradorite is found in plutonic rocks that cooled extremely slowly or underwent high-grade metamorphism; its bulk composition generally falls between An46±2 and An60±2, and individual crystals may reach several decimetres.
Evidence grade AScope: The setting and composition range of iridescent labradorite; not all labradorite occurrences are covered.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- MadagascarLight-bodied labradorite with multicolored sheen (traded as 'rainbow moonstone')
Sources GIA Moonstone Description
Europe
- Ylämaa, near Lappeenranta, FinlandSpecimen locality in HoM; no mention of labradorescence or gem use
Sources Handbook of Mineralogy
North America
- Labrador, Newfoundland and Labrador, CanadaGIA: this labradorite is found mainly in Labrador
Sources GIA Moonstone Description
- Paul Island, Labrador, CanadaType locality of labradorite
Sources 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.
Causes of colour and optical effects
The Bøggild intergrowth produces labradorite's iridescence. It consists of wider calcic lamellae (roughly 70-200 nm) alternating with thinner sodic lamellae (roughly 50-100 nm); these lie mostly parallel to the (3̄202) plane, which is why the interference colour can be seen on the (010) cleavage surface.
Evidence grade AScope: A description of the exsolution lamellae and observation surface; lamella sizes are literature-typical values.
The total thickness of the lamellae governs the interference colour: blue appears when adjacent calcic and sodic lamellae together measure about 150 nm, red when they exceed 250 nm, and a continuous spectrum lies in between. Within one crystal, colour zones also track composition directly - the red zone holds roughly 2-3 mol.% more calcic component than the blue one.
Evidence grade AScope: The thickness-colour and zone-composition relations; these are qualitative to semi-quantitative.
When a plagioclase solid solution cools, it can separate out (exsolution means the splitting of one homogeneous solid solution into two or more distinct phases), producing lamellae that may be periodic; optical effects such as labradorescence originate in these submicron exsolution textures.
Evidence grade AScope: The definition of exsolution and the phenomenon-texture link; exsolution also occurs in other mineral solid solutions.
Iridescent labradorite is often dark in bodycolour due to iron oxide inclusions; the darkness affects the appearance of the iridescence by controlling the depth at which light is reflected by the lamellae inside the crystal.
Evidence grade AScope: The relation between bodycolour and the appearance of iridescence; not all labradorite is dark.
Other research findings
The name labradorite, used on its own, denotes plagioclase feldspar whose composition lies between An50 and An70; labradorescence is the iridescent schiller that plagioclase feldspar labradorite from plutonic rocks can display.
Evidence grade AScope: The definition of labradorite and its optical phenomenon; the An boundaries are conventional.
Spectrolite, a rare variety of labradorite from Finland, is highly prized for its rich, full-spectrum colours and stronger labradorescence; it often shows several colours at once and is regarded as the most vivid example of the effect.
Evidence grade BScope: Describes what makes spectrolite prized in one journal's overview of phenomenal gems; it is not a graded list of quality factors and not a statement about the value of any piece.
Sources G&G in a Flash, Summer 2025
GIA uses "spectrolite" as the trade name for labradorite from Finland, found in a small area of the country's southeast, and describes it as a rare variety known for strong, full-spectrum labradorescence.
Evidence grade BScope: This is GIA's usage. The cited GIA pages name Finland as the source but give no exact deposit name (such as Ylämaa) and do not say whether labradorite from elsewhere may be sold under the name.
Sources GIA News (2016) · GIA News (2017) · G&G in a Flash, Summer 2025
- Optical Effects of Phenomenal Cabochons (GIA News & Research, November 10, 2016)
- Frozen Splendor: Gems and Minerals Near the Arctic Region (GIA News & Research, March 17, 2017)
- G&G in a Flash: Guide to Phenomenal Gems (Phoebe Shang; Gems & Gemology, Summer 2025, Vol. 61, No. 2; web version 2026-03-04)
CIBJO's standards list "spectrolite" as an accepted trade name for labradorite that shows labradorescence, alongside the plain name labradorite. The laboratory book's entry describes it by appearance only: grey to nearly black, translucent to opaque, with labradorescence producing interference colours at the surface. Neither entry states a required origin.
Evidence grade AScope: This records only what the CIBJO entries contain; the absence of an origin criterion does not amount to a CIBJO ruling that other origins may use the name. No authoritative statement on other-origin labradorite being passed off as spectrolite was found.
Sources CIBJO Gemstone Book 2022 · CIBJO Gemmological Laboratories Book 2024
CIBJO lists labradorite with labradorescence (labradorite or spectrolite) as commonly untreated. It records two occasional treatments, a near-colourless surface waxing and dyeing, and rates both as unstable.
Evidence grade AScope: Trade-level frequency estimates from one standard; they do not describe any particular stone.
Sources CIBJO Gemstone Book 2022
For untreated labradorite with labradorescence, CIBJO assigns two special-care notes beyond normal care: it can cleave or fracture easily, so wear it with care, and it can be damaged by ultrasonic cleaning, so keep it out of ultrasonic cleaners.
Evidence grade AScope: General care codes from a trade standard; waxed or dyed stones carry an extra note (clause 6.2 k).
Sources CIBJO Gemstone Book 2022
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The sources give no absolute age or duration for the exsolution or crystallization of iridescent labradorite.
- This record covers natural iridescent labradorite only, not synthetic, assembled, or copper-diffused material.
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
- Iridescent Labradorite
16 CFR Part 23 §23.24
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
Labradorite (Spectrolite) is Labradorite displaying full-spectrum labradorescence; use "Iridescent Labradorite" for listings, and disclose any known treatments.
Evidence
What this means for you
Before buying, check the recommended listing name "Iridescent Labradorite" 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
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); 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 Labradorite (Spectrolite), the name register records "Spectrolite", for which no restriction on use as a name is recorded.
Chinese standard nameThe national-standard name corresponding to Labradorite (Spectrolite) is labradorite (GB/T 16552—2017); the original GB/T 16552—2017 does not contain this name. Candidate search termsThe trade name/synonym Spectrolite is registered as an English market name and is a search candidate only. Recommended listing nameThe suggested listing name is spectrolite labradorite. Names in four languagesNames are given in Simplified Chinese, Traditional Chinese, English (Labradorite (Spectrolite)) and Japanese; the Japanese name is the entry's own, and which name GSJ (Japan) uses is not yet verified by this site. Trade and mineralogical namesThe mineralogical name refers to labradorite showing a full-spectrum labradorescence. Institution usageOn authority wording, CIBJO lists Labradorite; the FTC text contains no wording for this name (checked); GIA and Gem-A are unchecked, and unchecked bodies show the entry's own English name, which does not represent their position.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| SpectroliteEnglish | market name | search candidate only | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- ラブラドライト／スペクトロライト (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)
- 拉长石 (GB/T 16552—2017 §5.3.4)
- Mineralogical name
- Labradorite displaying full-spectrum labradorescence
- Trade names and synonyms
- Spectrolite (market name; conditional name)
Four-language names
- 简体中文
- 变彩拉长石
- 繁體中文
- 變彩拉長石
- English
- Labradorite (Spectrolite)
- 日本語
- ラブラドライト／スペクトロライト
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 Table B.1Labradorite (Spectrolite) is classified by applying the feldspar row of GB/T 16552—2017 Annex B Table B.1: filling is defined by grade; coating is listed as a treatment; diffusion treatment is listed as a treatment; irradiation is listed as a treatment. The notes to Table B.1 and the definitions of the filling grades are on the treatments page. JJA/AGL designationsIn the Japanese JJA/AGL 2025 table, the species for Labradorite is labradorite, the colour is colourless or bluish grey, and labradorescence is mentioned; a note explains that the original does not name spectrolite, which is a related entry.
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 name | Species | Colour | Listed in the table | Notes |
|---|---|---|---|---|
| Labradorite | Labradorite | colourless, bluish grey | listed under “Labradorite” in the table; this page is related (the source does not name it); labradorescence |
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 registered material facts for Labradorite (Spectrolite) take the values of the clause for feldspar as a whole mineral group and are not measurements of Labradorite (Spectrolite) alone. Under the feldspar clause, the overall structure is crystalline, and labradorite belongs to the triclinic crystal system; Mohs hardness is 6–6.5 and cleavage is two perfect directions. Under the feldspar clause, density of 2.55–2.75 g/cm³, refractive index of 1.508–1.572 and birefringence of 0.005–0.01 are overall values, as this site notes, because the clause has finer sub-ranges; optical character is anisotropic, biaxial positive or negative. Under the feldspar clause, pleochroism is usually none, in the untreated state; the optical effects that can be seen are iridescence, chatoyancy, asterism and aventurescence; lustre is vitreous, in the untreated state. Chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are written for feldspar as a whole mineral group; see the material facts on the Feldspar entry.
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Chemical composition, luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for feldspar (the whole mineral group), so they are not repeated on the Labradorite (Spectrolite) 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 Labradorite (Spectrolite) (how to read class-level values).
Structure
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Iridescent Labradorite — 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
Testing and market
The CIBJO laboratory protocol covers Labradorite (Spectrolite) under “Feldspar” (§6.1.34): 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.
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.
- GIA – Gemological Institute of America (United States). Gem Encyclopedia.
- Gem-A – The Gemmological Association of Great Britain (United Kingdom).
- eCFR (United States). 16 CFR § 23.24 — Disclosure of treatments to gemstones. In: 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries.
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 (Labradorite (Spectrolite)) is marked.
- Feldspar
Sub-entries (12)
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 Labradorite (Spectrolite) 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.