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Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown
Orthoclase
Also known asYellow Orthoclase
A potassium feldspar mineral species in the feldspar group and one of the main components of classic moonstone. Under GB/T §5.1.1 b), its mineral name can be used directly as a gem name. 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 Orthoclase 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 OrthoclaseHow far lab testing can go and whether a synthetic exists
- Treatments and enhancements of OrthoclaseThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing OrthoclaseCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of OrthoclaseEach value with its source and check date
- Orthoclase 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 OrthoclaseThe listing name to use
- Standard clauses that define OrthoclaseWhich 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
Orthoclase is the potassium feldspar species of the feldspar group, with formula KAlSi3O8, and is the monoclinic member of the alkali feldspar subgroup. As a rock-forming mineral it occurs widely in many rocks; orthoclase-type sunstone (with hematite film inclusions) is found mainly in granites or pegmatites. In slowly cooled potassium feldspar, the sodium-rich albite component can exsolve as albite lamellae, forming a perthite (or cryptoperthite) intergrowth with the potassic host; when this exsolution texture consists of submicron, periodically alternating albite–orthoclase lamellae, interference of white light produces the classic blue ‘moonlight’ glow — the commercially important orthoclase-type moonstone.
Scope: Covers the formation environment and exsolution-related optical-effect mechanism of orthoclase (KAlSi3O8) as a potassium feldspar mineral species; does not cover details of other potassium feldspar species such as microcline and sanidine.
Sources G&G Summer 2025 · G&G Summer 2024 · G&G Spring 2024
- Structures Behind the Spectacle: A Review of Optical Effects in Phenomenal Gemstones and Their Underlying Nanotextures
- Gem-Quality Anorthoclase Feldspar from Southeast Vietnam (Gems & Gemology, Summer 2024, Vol. 60, No. 2)
- New High-Quality Rainbow Moonstone from Madagascar (Gems & Gemology, Spring 2024, Vol. 60, No. 1)
Where it forms
Granites and granitic pegmatites: the main occurrence of orthoclase-type sunstone (hematite film inclusions).
Sources G&G Summer 2025
A rock-forming mineral of many igneous and metamorphic rocks; the alkali feldspar subgroup varies continuously between the albite and orthoclase compositions.
Sources G&G Summer 2024 · G&G Summer 2025
How it forms, step by step
K-rich melts/fluids crystallize orthoclase (KAlSi3O8), with the albite component entering the potassic lattice in solid solution.
Sources G&G Summer 2024 · G&G Spring 2024 · G&G Summer 2025
- Gem-Quality Anorthoclase Feldspar from Southeast Vietnam (Gems & Gemology, Summer 2024, Vol. 60, No. 2)
- New High-Quality Rainbow Moonstone from Madagascar (Gems & Gemology, Spring 2024, Vol. 60, No. 1)
- Structures Behind the Spectacle: A Review of Optical Effects in Phenomenal Gemstones and Their Underlying Nanotextures
On slow cooling the solid solution exsolves, with the albite component separating as lamellae from the potassic host, forming a perthite/cryptoperthite intergrowth.
When the exsolved lamellae reach a submicron, periodically alternating scale, white light interferes at the albite–orthoclase interfaces, producing the blue ‘moonlight’ glow.
In granitic/pegmatitic settings with hematite film inclusions, orthoclase can additionally show aventurescence (sunstone effect).
Link to appearance
Orthoclase is itself colorless to pale; with periodic albite–orthoclase exsolution lamellae it shows blue moonstone adularescence, and with hematite film inclusions it shows sunstone aventurescence.
Sources G&G Summer 2025 · G&G Spring 2024
Timescale
The sources give no absolute age or duration for orthoclase or its exsolution textures.
Sources G&G Summer 2025
Related base materials
- Feldspar group: Mineral group to which it belongs
- Alkali feldspar subgroup: Orthoclase is the monoclinic potassium feldspar of the alkali feldspar subgroup
Supporting findings
Orthoclase-type sunstone is found mainly in granites or pegmatites, where oriented hematite (oxidised magnetite) film inclusions produce aventurescence and can show iridescence by thin-film interference.
Evidence grade AScope: Concerns hematite-film orthoclase; excludes copper sunstone (labradorite).
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Itrongay, near Betroka, MadagascarHoM notes gem crystals
Sources Handbook of Mineralogy
Seas and coasts
- Worldwidea common rock-forming mineral
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
A phenomenal variety of orthoclase, blue moonstone owes its blue 'moonlight' to light interference set up by the microscopic albite and orthoclase layers that alternate within it.
Evidence grade AScope: Applies to orthoclase-type moonstone with albite–orthoclase exsolution lamellae; excludes assembled or filled material.
Other research findings
Orthoclase is the monoclinic potassium feldspar species (KAlSi3O8) of the feldspar group; the alkali feldspar subgroup runs from albite (NaAlSi3O8) to orthoclase (KAlSi3O8), covering monoclinic sanidine and orthoclase plus triclinic anorthoclase, albite and microcline.
Evidence grade AScope: Species/subgroup classification; orthoclase shares K-feldspar chemistry with sanidine and microcline but differs in symmetry.
Strictly speaking, the name 'moonstone' belongs only to cryptoperthite — an alkali feldspar in which albite and orthoclase are intergrown in nonperiodic submicron textures; orthoclase is but one possible host.
Evidence grade AScope: Follows GIA’s strict definition of ‘moonstone’; the trade applies the name loosely.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The sources give no quantitative formation temperature/pressure or age for orthoclase (or moonstone).
- Distinguishing orthoclase from sanidine and microcline relies on crystal structure (e.g. XRD, Raman); routine gemmology cannot separate them.
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
- Orthoclase
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)
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
Orthoclase is Orthoclase feldspar; use "Orthoclase" 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 "Orthoclase" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
- 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
Orthoclase — 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, Orthoclase, p.53; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Orthoclase — 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, Orthoclase, p.53; §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
CleaningOn whether Orthoclase can be cleaned ultrasonically, the care conclusion for Orthoclase in the CIBJO Blue Book The Gemstone Book (2022) is that it must not be cleaned ultrasonically; the same source states, on wear, that Orthoclase breaks easily, so wear it with care. Both conclusions apply in any treatment state. General careGeneral care that applies to every gemstone in the CIBJO Gemstone Book, and the full table of special-care letters, are in the general care section of the materials index page.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Wearing limits (knocks, settings) | 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 Orthoclase, the name register records "Orthoclase" and "Yellow Orthoclase", for which no restriction on use as a name is recorded (CIBJO Gemstone Book 2022 Annex 8 “Yellow Orthoclase”).
Standard and listing namesThe GB/T 16552—2017 Chinese formal name for Orthoclase comes from the “Moonstone” row of Table A.1, and the suggested listing name is Orthoclase. Trade and mineralogical namesThe trade name or synonym is recorded as Orthoclase, and the mineralogical name is Orthoclase feldspar. Names in four languagesThe four-language names are given in Simplified Chinese, Traditional Chinese, English (Orthoclase) and Japanese (a transliteration and a kanji name); the Japanese GSJ formal name is the kanji name. Institution usageAmong authority wordings, CIBJO lists Orthoclase (CIBJO Gemmological Laboratories Book 2024); the FTC has been checked, and its source text has no wording for Orthoclase; GIA and Gem-A have not yet been checked. Bodies without a recorded wording show the entry's own English name, which does not represent their position. Sub-names and unacceptable namesYellow Orthoclase is also registered, a subordinate name listed in Annex 8 of the CIBJO Gemstone Book 2022.
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 (2) | ||||
| OrthoclaseEnglish | synonym | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| Yellow OrthoclaseEnglish | narrower name (variety or subtype) | matched automatically | no restriction recorded | CIBJO Gemstone Book 2022 Annex 8 “Yellow Orthoclase” |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 正長石
- Chinese formal name
- 正长石 (GB/T 16552—2017 Table A.1, row “Moonstone”)
- Mineralogical name
- Orthoclase feldspar
- Trade names and synonyms
- Yellow Orthoclase (narrower name (variety or subtype))
Four-language names
- 简体中文
- 正长石
- 繁體中文
- 正長石
- English
- Orthoclase
- 日本語
- オーソクレース／正長石
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 species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T Table B.1The optimizations and treatments for Orthoclase under GB/T 16552—2017 Annex B, Table B.1 are applied by this site from the Feldspar row of Table B.1; the standard registers the Feldspar row and does not list Orthoclase separately. Under the Feldspar row of Table B.1, filling must be graded, with the grades defined on this site's Gem treatments page; coating, diffusion and irradiation are all classed as treatment. See alsoThe notes to Table B.1 are likewise on this site's Gem treatments page, and 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 chemical formula of Orthoclase, registered for potassium feldspar (the whole subgroup), is KAlSi3O8, possibly with Ba, Na, Rb, Sr and other elements. Registered for feldspar (the whole mineral group): structure overall crystalline; Mohs hardness 6–6.5, with two perfect cleavages; optic character anisotropic, biaxial, optically positive or negative; pleochroism usually none, untreated; quality factor (lustre) vitreous, untreated. For the density of 2.55–2.75 g/cm³, refractive index of 1.508–1.572 and birefringence of 0.005–0.01 registered for feldspar (the whole mineral group), the site notes that these are the clause's overall values, as the clause also gives finer sub-ranges. Orthoclase is transparent; its body colour is colourless or yellow, untreated; the site notes that in Chapter 7 of the CIBJO Gemmological Laboratories Book the colour descriptions for entries such as brazilianite, achroite and bytownite also mention colourless.
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 Orthoclase 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 Orthoclase (how to read class-level values).
Definition
Orthoclase — nomenclature status: IMA status A: approved (accepted by the IMA after it was set up in 1958).
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Orthoclase — composition (chemistry): potassium feldspar: KAlSi3O8; may contain Ba, Na, Rb, Sr and other elements.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- potassium feldspar (the whole sub-group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Chemical composition · Potassium feldspar (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Orthoclase — composition (phase): orthoclase (Feldspar group)
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Orthoclase — 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
Orthoclase — 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
Orthoclase — 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
Mohs hardness2 sources compared
Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, 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))
Orthoclase — Mohs hardness: 6–6.5
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
Orthoclase — Mohs hardness: 6–6.5
Handbook of Mineralogy
- Qualification
The source we cite gives a Mohs hardness but no figure for toughness or stability.
- General note
- hardness only, not durability
Source & check 2026-10-08
- Source
- Handbook of Mineralogy — Orthoclase: p. 1, Physical Properties (locator checked 2026-10-08)
- Fact checked on
- 2026-10-08
Orthoclase — 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
Orthoclase — 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 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Orthoclase — 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
Orthoclase — 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 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Orthoclase — 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 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Orthoclase — transparency: transparent.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Orthoclase — 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
Orthoclase — 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
Orthoclase — 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
Orthoclase — 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
Orthoclase — 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
Orthoclase — body colour: Colourless, yellow.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Brazilianite, Achroite, Bytownite and other entries also name colourless.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
- CIBJO definitions
- chatoyancy, asterism, aventurescence
Quality factors
Orthoclase — 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 lists Orthoclase under “Feldspar”: identification details are in the identification part of the Feldspar entry, and the required tests are listed on the laboratory testing page. As for the market, no synthetic counterpart of Orthoclase is on the market.
The CIBJO laboratory protocol covers Orthoclase 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
Orthoclase — 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
Orthoclase is defined directly in the CIBJO Gemmological Laboratories Book 2024, under the term Orthoclase, with the definition colourless, yellow, transparent, and a note to see also moonstone. The cross-check result is that it is defined directly by CIBJO, and no identically named English entry was found in this edition of the GB/T annex.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Orthoclase | 7.2.1.168 | Colourless, yellow, transparent. See also moonstone | 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
Further reading
Related entries and topic cluster
Parent entry and related pages on this site. Rows marked “Planned” are suggested new content and have no link yet.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | 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 Orthoclase 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.