On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Oligoclase
A feldspar with a composition between Albite and Andesine. Sunstone is often mainly oligoclase, and the exact species must be confirmed by testing. Also known as Sunstone. 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 Oligoclase 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 OligoclaseHow far lab testing can go and whether a synthetic exists
- Treatments and enhancements of OligoclaseThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing OligoclaseCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of OligoclaseEach value with its source and check date
- Oligoclase 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 OligoclaseThe listing name to use; what must be disclosed before sale
- Standard clauses that define OligoclaseWhich clause defines it, each cross-checked
What we cannot conclude
- Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.
- Geographic origin, unless an origin report accompanies the item.
- Price, rarity or investment value: this wiki covers naming and disclosure only.
Material research: formation, causes and history
What authoritative sources say about how this material forms, what causes its colour and optical effects, where its name comes from and how people have used it. Each statement carries an evidence grade and its sources; it describes the material in general, not any specific piece.
How it forms
Oligoclase is a sodic variety of the plagioclase solid-solution series, defined by its An content between albite and andesine (about An10-30 by convention). It is not an independent mineral species but a compositional-range name within the plagioclase continuous solid solution (albite NaAlSi3O8 - anorthite CaAl2Si2O8): plagioclase is a continuous solid solution between albite and anorthite, with composition expressed by An (mol.% anorthite). Oligoclase occurs in plutonic and metamorphic rocks such as granites and pegmatites; in pegmatites, pure low albite (~An0) can exsolve with minor oligoclase (~An20). Sodic plagioclase also commonly hosts thin-film and platy iron oxide (hematite or magnetite) inclusions that can produce thin-film interference and iridescence, as in the oligoclase 'confetti sunstone' from Tanzania.
Scope: Applies to the composition, environment and inclusion features of natural oligoclase as the name for the sodic range of the plagioclase series; does not cover andesine / labradorite material artificially coloured (e.g. by copper diffusion).
Sources G&G Summer 2025
Where it forms
Plutonic rocks and pegmatites: oligoclase occurs in granites and pegmatites, and thin-film iron oxide inclusions are mostly found in sodic plagioclase and alkali feldspars.
Sources G&G Summer 2025
Pegmatitic exsolution setting: pure low albite exsolves with minor oligoclase.
Sources G&G Summer 2025
How it forms, step by step
Plagioclase of oligoclase composition (about An10-30) crystallizes from sodium-rich to intermediate plagioclase melts/fluids.
During cooling in pegmatites, pure low albite exsolves with minor oligoclase (~An20).
Thin-film and platy hematite or magnetite inclusions develop in sodic plagioclase, producing thin-film interference iridescence.
Its range name (oligoclase) is defined by An content and must be confirmed by compositional analysis.
Link to appearance
Oligoclase is a compositional range of the plagioclase series; its thin-film iron oxide inclusions can produce iridescence/aventurescence (as in the Tanzanian oligoclase 'confetti sunstone'). Neither the range name nor the appearance alone proves identity, which requires compositional testing.
Sources G&G Summer 2025
Timescale
The sources give no absolute age or duration for oligoclase crystallization or exsolution.
Sources G&G Summer 2025
Related base materials
- Plagioclase solid-solution series (albite-anorthite): range-of | Oligoclase is the name of a sodic range of the plagioclase solid-solution series, defined by An content
Supporting findings
In pegmatites, pure low albite (~An0) exsolves with minor oligoclase (~An20); oligoclase is the minor phase in this exsolution assemblage.
Evidence grade AScope: From the description of sodic plagioclase (peristerite); oligoclase is the minor phase.
Sunstone (aventurescent feldspar) has two principal reflective inclusion types — metallic copper and iron oxides. Where hematite provides the inclusions, the host rock is usually granite or pegmatite, and such sunstones fall into an orthoclase group and a sodic-plagioclase group (oligoclase or albite).
Evidence grade AScope: Describes the setting of iron-oxide-bearing sunstones; oligoclase is their sodic-plagioclase category.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Europe
- Tvedestrand, Norway
Sources Handbook of Mineralogy
- Arendal, Norway
Sources Handbook of Mineralogy
- Danviken, near Stockholm, Sweden
Sources Handbook of Mineralogy
- Bodenmais, Bavaria, Germany
Sources Handbook of Mineralogy
North America
- Corundum Hill, Chester County, Pennsylvania, United States
Sources Handbook of Mineralogy
Seas and coasts
- Worldwide
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
Inclusions of iron oxide in thin-film or platy form (hematite, magnetite) occur mainly in alkali feldspars and sodic plagioclase, where they can generate thin-film interference and iridescence — as in the Tanzanian oligoclase called 'confetti sunstone'.
Evidence grade AScope: A general note on inclusion-composition relations and the optical effect; not all oligoclase shows it.
Other research findings
Oligoclase is a sodic variety of the plagioclase solid-solution series defined by An content, lying between albite and andesine; it is not an independent mineral species.
Evidence grade AScope: A range-name statement; the specific boundaries (about An10-30) are conventional.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The sources do not define the exact An limits of oligoclase; the range used here (about An10-30) is conventional.
- The sources give no absolute age or duration for oligoclase crystallization or exsolution.
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
- Oligoclase
GB/T 16552—2017 5.1.1 b)
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
Oligoclase is Oligoclase; feldspar variety between albite and andesine in composition; use "Oligoclase" for listings, and disclose any known treatments.
Evidence
- GB/T · 5.1.1 b)
What this means for you
Before buying, check the recommended listing name "Oligoclase" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- Last reviewed
- 2026-09-01
Care and wear
Normal care for every gemstone (CIBJO Gemstone Book §6.1), in brief:
- Handle it gently.
- Store pieces apart when not worn, so they cannot scratch each other.
- Clean with warm soapy water and a soft brush.
- Use ultrasonic cleaners only with caution.
The §6.1 wording and the full list of §6.2 special-care letters cited on this page are on the general gem care page.
Care
Oligoclase — care (cleaning): Some stones are susceptible to damage from ultrasonic cleaning. Do not expose them to ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code j
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Oligoclase, p.52; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Oligoclase — 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
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Oligoclase, p.52; §6.2 b (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Common care questions and matching entries
CleaningOligoclase must not be cleaned ultrasonically, in any treatment state; the conclusion comes from the CIBJO Blue Book — Official Gemstone Book (2022). WearOligoclase cleaves or fractures easily, so wear it with care, in any treatment state; this conclusion also comes from the CIBJO Blue Book — Official Gemstone Book (2022). General careGeneral care that applies to all gems is given in the general care part of the material entries index page.
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| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Wearing limits (knocks, settings) | cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care |
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
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 Oligoclase, the name register records "Sunstone", for which no restriction on use as a name is recorded.
Standard and listing namesThe Chinese formal name for Oligoclase is based on the Sunstone row of GB/T 16552—2017 Table A.1, and the suggested listing name is Oligoclase. Names in four languagesFour-language names are given in Simplified Chinese, Traditional Chinese, English (Oligoclase) and Japanese; the Japanese name is the entry's own registration, and the wording of Japan's GSJ for this name is not yet verified by this site. Trade and mineralogical namesThe mineralogical name is Oligoclase, a feldspar variety between albite and andesine in composition; trade names or synonyms include Sunstone, which may include oligoclase, and the name register lists Sunstone as an English market name, matched only once the conditions are confirmed. Institution usageOn authority wording, CIBJO records Oligoclase (CIBJO Gemmological Laboratories Book 2024); the FTC text has been checked and has no wording for this name; GIA and Gem-A wording is unchecked. Bodies without a recorded wording 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.
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| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| SunstoneEnglish | market name | matched only once the condition is confirmed | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- オリゴクレース／灰曹長石 (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 奥长石 (GB/T 16552—2017 Table A.1, row “Sunstone”)
- Mineralogical name
- Oligoclase; feldspar variety between albite and andesine in composition
- Trade names and synonyms
- Sunstone (market name; conditional name)
Four-language names
- 简体中文
- 奥长石
- 繁體中文
- 奧長石
- English
- Oligoclase
- 日本語
- オリゴクレース／灰曹長石
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
For Oligoclase, GB/T 16552—2017 Annex B, Table B.1 is applied from the "Feldspar" row: filling, graded as set out in the cited grading notes; coating is a treatment; diffusion is a treatment; irradiation is a treatment. What Table B.1 is, and how the grades are defined, are on the Gem treatments page; the full row with the effect column is on the Feldspar 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.
What it is and how it's identified
The composition of Oligoclase is taken for plagioclase (the whole series), lying between NaAlSi3O8 and CaAl2Si2O8; structure, durability, density, optic character, pleochroism, optical effects and lustre are taken for feldspar (the whole mineral group), not measured on Oligoclase separately. For feldspar (the whole mineral group), Oligoclase is crystalline, with Mohs hardness 6–6.5 and two directions of perfect cleavage; density is 2.55–2.75 g/cm³, refractive index 1.508–1.572 and birefringence 0.005–0.01, and this site notes that the clause has further sub-grades and the overall value is registered; the optic character is anisotropic, biaxial positive or negative. For feldspar (the whole mineral group), untreated Oligoclase usually shows no pleochroism and has a vitreous lustre. For feldspar (the whole mineral group), iridescence, the cat's-eye effect, asterism and aventurescence can all 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 Oligoclase 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 Oligoclase (how to read class-level values).
Definition
Oligoclase — composition (chemistry): plagioclase: NaAlSi3O8–CaAl2Si2O8.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- plagioclase (the whole series)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Chemical composition · Plagioclase (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Structure
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — 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
Oligoclase — body colour: Green oligoclase may look similar to amazonite.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Aventurine Quartz, Diopside, Emerald and other entries also name green or a greenish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, asterism, aventurescence
Quality factors
Oligoclase — 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
In the CIBJO laboratory protocol, Oligoclase is placed under “Feldspar”; for identification methods and the list of required tests, see the identification section of the Feldspar entry and the laboratory testing page. No synthetic Oligoclase is available on the market.
The CIBJO laboratory protocol covers Oligoclase 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
Oligoclase — synthetic counterpart on the market: No synthetic counterpart of this material is commercially available
CIBJO Gemstone Book 2022
- Treatment state
- any treatment state
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Oligoclase has a direct definition in the CIBJO Gemmological Laboratories Book 2024 under the entry Oligoclase, and the CIBJO wording is quoted in full under Clause-level definitions on this page. The cross-check result is a direct CIBJO definition; no identically named English entry was found in this edition of the GB/T annex.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Oligoclase | 7.2.1.158 | A plagioclase feldspar with an albite : anorthite molar ratio ranging from 90 : 10 to 70 : 30. Green oligoclase may look similar to amazonite | Defined 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
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).
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 (Oligoclase) 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 Oligoclase 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.