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
White Opal
A natural opal variety with a white background body color, with the GB/T 16552-2017 Table A.2 basic name "White Opal"; whether it shows play-of-color must be stated for each item. 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 White Opal 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 White OpalIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of White Opal1 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing White OpalCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of White OpalEach value with its source and check date
- White Opal in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name, names in national standards; and: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Listing and disclosing White OpalThe listing name to use; what must be disclosed before sale
- Standard clauses that define White OpalWhich 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
White opal—sometimes called light opal—is a natural opal variety in which play-of-color shows over a white or light gray bodycolor. It forms naturally: rain carries dissolved silica into ancient rock underground, dry spells evaporate the water, and silica settles in cracks and between layers of underground sedimentary rock as hydrated amorphous silica. Sub-microscopic silica spheres stacked in a grid-like pattern build the opal; light waves travelling between these spheres diffract and separate into spectral colours, which is what produces play-of-color. The white or light gray bodycolor merely forms the background and is unrelated to the diffraction responsible for the play-of-color.
Scope: Applies to the origin and body colour of natural white/light-coloured opal; does not apply to other body-colour varieties such as black opal and fire opal.
Sources GIA Opal Description · GIA Opal
Where it forms
Ancient underground sedimentary rock in semi-desert ‘outback’ regions such as Australia’s (the rainwater-infiltration zone)
Sources GIA Opal Description
How it forms, step by step
Seasonal rains soak deep into ancient underground rock carrying dissolved silica.
Sources GIA Opal Description
During dry periods much of the water evaporates, leaving solid silica deposits in cracks and between layers of sedimentary rock.
Sources GIA Opal Description
The silica spheres stack and consolidate into hydrated amorphous opal; light diffracting between ordered spheres produces play-of-color.
Sources GIA Opal Description · GIA Opal
Link to appearance
White opal’s play-of-color comes from diffraction of light by ordered silica spheres; the white/light gray bodycolor is the background and has a different cause.
Sources GIA Opal Description · GIA Opal
Timescale
The cited sources give no absolute timescale for natural opal formation.
Sources GIA Opal Description · GIA Opal
Supporting findings
Natural opal forms as seasonal rains carry dissolved silica into underground rock and dry-period evaporation precipitates the silica as deposits.
Evidence grade AScope: Describes a sedimentary-pathway formation using Australia’s outback as the example; not every locality is covered.
Sources GIA Opal Description
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Wegel Tena, Wollo, EthiopiaG&G: material from this deposit (found 2008) is mostly white
Sources Gems & Gemology Summer 2010
Oceania
- White Cliffs, New South Wales, Australia
Sources GIA Gem Encyclopedia
- Mintabie, South Australia, Australia
Sources GIA Gem Encyclopedia · GIA Opal Description
- Andamooka, South Australia, Australia
Sources GIA Gem Encyclopedia
- Coober Pedy, South Australia, Australia
Sources GIA Gem Encyclopedia · GIA Opal Description
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
Opal’s play-of-color arises from diffraction of light by sub-microscopic silica spheres stacked in a grid-like pattern, breaking white light into spectral colors.
Evidence grade AScope: A qualitative mechanism; the cited sources give no quantitative diffraction equations.
Sources GIA Opal Description · GIA Opal
How it is identified
White opal resembles synthetic or imitation material in appearance, so looks alone cannot decide. The distinction must be made in a laboratory through composition and structure testing (including whether water is present), combined with microscopy and spectroscopic instruments; the conclusion should be issued by an accredited laboratory.
Evidence grade AScope: Determining white opal's origin/type is laboratory testing, to be issued by an accredited body.
Other research findings
Also termed light opal, white opal is a variety whose play-of-color appears over a background bodycolor of white or light gray, the stone itself being translucent to semitranslucent.
Evidence grade AScope: A GIA descriptive definition of the variety; it gives no locality or bodycolor-cause detail.
Sources GIA Opal Description
Opal can contain up to about 20% water trapped in its silica structure.
Evidence grade BScope: A general figure from GIA; it does not differentiate among varieties.
Sources GIA Opal
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The cited sources do not detail white opal’s specific localities or the causes of its bodycolor (e.g., inclusion species).
- The cited sources give no absolute timescale for natural opal formation.
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
- White Opal
GB/T 16552—2017 Table A.2 “White Opal” · IMA Mineral List 2026-07 “Opal”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Filled / Fracture-filled (via parent material), Dyed (via parent material), Coated (via parent material), Impregnated
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
White Opal is White-background natural opal variety; use "White Opal" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.2, row 白欧泊 (White Opal)
What this means for you
Before buying, check the recommended listing name "White Opal" 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.
The item-by-item care advice that the GIA Care and Cleaning Guide gives for the whole class, and so for White Opal, is set out in full under care on the Opal entry.
Care
White Opal — care (chemicals): Treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code k
- Treatment state
- treated
- Only after these treatments
- impregnation
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, White Opal, p.63; §6.2 k (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
White Opal — care (special care): impregnated with colourless plastic to improve durability and appearance: special care (SC); avoid heat.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- impregnation
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.XII, Gemstone Information Chart, Opal White, Black & Semi-Black I, CARE REQUIRED / SPECIAL ADVICE (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
White Opal — care (special care): impregnated with colourless oil, wax or resin: special care (SC); avoid heat.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- fissure filling with oil, fissure filling with resin
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.XII, Gemstone Information Chart, Opal White, Black & Semi-Black O, CARE REQUIRED / SPECIAL ADVICE (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.
Common care questions and matching entries
ChemicalsCare for White Opal: where the treatment state is treated, and only for impregnated White Opal, the CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) states that treatments with dye, oil, resin, wax or plastic are not permanent, and the stone must be kept away from all solvents (including all dish-washing liquids), chemicals and heat. Special careWhere the treatment state is treated, and only for impregnated White Opal, the AGTA (American Gem Trade Association) Gemstone Information Manual, 17th edition, states that stones impregnated with colourless plastic to improve durability and appearance need special care (marked SC) and must be kept away from heat. Where the treatment state is treated, and only for White Opal with fissures filled with oil or resin, the AGTA Gemstone Information Manual, 17th edition, states that stones impregnated with colourless oil, wax or resin need special care (marked SC) and must be kept away from heat. CleaningThe GIA (Gemological Institute of America) care and cleaning guide is given for the class as a whole and also applies to White Opal; the item-by-item care advice is listed in full in the care section of the Opal entry.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Contact with acids, alkalis and household chemicals | Treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat |
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.
treated (Only after these treatments: impregnation)
- Treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat §6.2 k
- impregnated with colourless plastic to improve durability and appearance: special care (SC); avoid heat
treated (Only after these treatments: fissure filling with oil, fissure filling with resin)
Treatments and identification leads
Registered treatmentsThe treatment registered for White Opal is impregnation. Stability and frequencyImpregnation has status treated, stability not stable and market prevalence rare. Values not givenThe identification leads and source for impregnation are both given as "—" in the register, and "—" means the cited source gives no value, not "none".
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| impregnationStatus: treated | rarely | unstable | — | impregnation with a colourless agent | — |
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Dyeing | — | — | Treatment | — | — |
| Coating | — | — | Treatment | — | — |
Where each treatment acts (schematics): Impregnated
“—” means the cited source gives no value for that item, not “none”. Source: CIBJO Gemstone Book 2022; GB/T 16552—2017 Table B.1 (row for Opal); 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
Standard and listing namesThe formal name for White Opal is given in GB/T 16552—2017 Table A.2, and the suggested listing name is White Opal. Names in four languagesThe four-language names are given in Simplified Chinese, Traditional Chinese, English (White Opal) and Japanese (a transliteration). Trade and mineralogical namesThe mineralogical name is a natural opal variety with a white background. Institution usageAmong authority wordings, CIBJO lists White Opal (CIBJO Gemmological Laboratories Book 2024), the FTC source text has no wording for this name (checked), and GIA and Gem-A have not been checked; bodies without a recorded wording show White Opal's own English name, which does not represent their position. Japanese namesWhite Opal's own Japanese name is a transliteration, and the Japanese GSJ wording for it is not yet verified by this site. Australia (GAA) writes White Opal, noting that Coober Pedy and Andamooka are the main sources.
- GSJ (Japan) formal name
- ホワイトオパール (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 白欧泊 (GB/T 16552—2017 Table A.2)
- Mineralogical name
- White-background natural opal variety
Four-language names
- 简体中文
- 白欧泊
- 繁體中文
- 白歐泊
- English
- White Opal
- 日本語
- ホワイトオパール
National and regional formal names
- Australia (GAA)
- White Opal; Coober Pedy and Andamooka are major sources
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Opal and natural amorphous silica materials
- Identity tier
- Mineral / gemstone variety
- Mineral chemical class
- Not applicable
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T Table B.1For White Opal, this site applies the Opal row of GB/T 16552—2017 Annex B, Table B.1, which lists filling, dyeing and coating; dyeing and coating are classed as treatment, and filling is graded, with the grades defined on the Gem treatments page. JJA/AGL designationsThe table of principal gem names in the JJA/AGL (Japan) definitions and nomenclature, November 2025 revision, lists White Opal under the species opal, in white, with the note play-of-colour; the table lists an untreated tier separately and records impregnation with a colourless agent (impregnated). See alsoThe notes to Table B.1 are on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Opal” row of Table B.1: Filling Graded — see §5.4.1, Table 1; Dyeing Treatment; Coating Treatment. The full row, with the effect column, is on the Opal 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 |
|---|---|---|---|---|
| White Opal | Opal | white | an untreated tier is listed; impregnation with a colourless agent (Impregnated) | play of colour |
JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.9
How to read the JJA/AGL table: see the Gem treatments page.
What it is and how it's identified
White Opal is opal with a white body colour and play-of-colour; its composition (phase) is opal, and its transparency is translucent to nearly opaque. Taken for opal (the whole class): the structure is amorphous, there is no cleavage, the optic character is isotropic, there is no birefringence, and when untreated the lustre is vitreous to resinous. Mohs hardness is 5–6.5; the cited clause covers the whole species, White Opal being only one variety within it. Density and refractive index are also taken for opal (the whole class): the density of 1.25–2.23 g/cm³ is derived from the clause value of 2.15 with a tolerance (+0.08/−0.90), and the refractive index of 1.37–1.47 from the clause value of 1.450 with a tolerance (+0.020/−0.080); this site notes that the clause has further sub-grades and the overall value is registered.
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Chemical composition, luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for opal (whole class), so they are not repeated on the White Opal page; see the material facts on the Opal entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of White Opal (how to read class-level values).
Definition
White Opal: opal with a white body colour and play of colour
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): §5.2.3 Colour · White opal (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
White Opal — composition (phase): opal
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
White Opal — structure (overall): amorphous (not crystalline)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
White Opal — Mohs hardness: 5–6.5
GIA Opal
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))
- Qualification
The clause we cite covers the whole species. This entry is only one variety of it.
Source & check 2026-09-20
- Source
- GIA Gem Encyclopedia — Opal (Gemological Institute of America): Section “FACTS”, “Mohs Hardness” (locator checked 2026-09-28)
- Fact checked on
- 2026-09-20
White Opal — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
White Opal — stability: chips and cracks easily; porous, so keep it away from coloured liquids; will craze if it loses water, so keep it away from heat and dry air; avoid sudden temperature changes; no ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code b, special-care code c, special-care code d, special-care code e, special-care code j
- Treatment state
- untreated
Source & check 2026-09-21
- Source
- Fact checked on
- 2026-09-21
For White Opal, the stability of impregnation is “unstable”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- impregnation
Source & check 2026-09-25
- Source
- Fact checked on
- 2026-09-25
Physical properties
White Opal — density: 1.25–2.23 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
- Qualification
The clause we cite gives 2.15, with a stated tolerance of +0.08 / -0.90. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
White Opal — optic character: isotropic; fire opal commonly shows anomalous extinction.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
White Opal — refractive index: 1.37–1.47
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
- Qualification
The clause we cite gives 1.450, with a stated tolerance of +0.020 / -0.080. The range shown here is worked out from that.
- General note
- the clause has finer ranges
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
White Opal — birefringence: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
White Opal — transparency: translucent to nearly opaque.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
White Opal — pleochroism: none
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
White Opal — fluorescence (overall): black or white body colour: none to moderate, white to light blue; green, yellow; may be phosphorescent.
GB/T 16553—2017
UV fluorescencewhitelight bluenone–moderate, black or white body colourgreenyellowblack or white body colourDots are illustrative colours built from the colour names, not measured values
- 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): §5.2.3 Fluorescence (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
optical effect (play of colour)2 sources compared
White Opal — optical effect (play of colour): Play-of-colour.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
White Opal — optical effect (play of colour): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
White Opal — optical effect (chatoyancy): seen; rare
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
White Opal — body colour: a white body colour.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Onyx, Amazonite, Charoite and other entries also name white or a whitish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
- CIBJO definitions
- play of colour, chatoyancy
Quality factors
White Opal — quality factor (lustre): vitreous to resinous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- opal (whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.3 (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): 1.42 / 1.74; Closest values: 1Synthetic Opal 1.45 / 2.08, 2Mammoth Ivory 1.53 / 1.75, 3Ivory 1.535 / 1.85, 4Hackmanite 1.483 / 2.27, 5Chrysocolla 1.516 / 2.2
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 White Opal under “Opal” (§6.1.56): see identification on the Opal entry; the required tests are listed on the CIBJO laboratory protocol table for Opal.
How far testing can go
For White Opal in trade, the reported frequency of impregnation is “rarely”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- impregnation
Source & check 2026-09-25
- Source
- 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.
Clause-level definitions
White Opal is listed directly and defined in the CIBJO Gemmological Laboratories Book 2024 under the entry White opal; the definition gives the mineral species as opal and the mineral/gem variety as white opal, with the CIBJO wording quoted in full under Clause-level definitions on this page. The cross-check result is: defined directly by CIBJO, and also appears in the GB/T annex.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| White opal | 7.2.1.262 | Play-of-colour against a white body colour, translucent to nearly opaque | Defined directly by CIBJO; also present in 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.
- RRUFF Project, in partnership with the IMA – International Mineralogical Association. IMA Mineral List.
- Geological Survey of Japan, AIST (Japan). Museum mineral specimens, browse by classification.
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 Opal on this site: 17 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (White Opal) is marked.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Opal and natural amorphous silica materials | Live |
| Treatments recorded for this material | Filled / Fracture-filled (via parent material), Dyed (via parent material), Coated (via parent material), Impregnated | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the White Opal 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.