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
Matrix Opal
Opal spread as fine specks or veinlets through a sedimentary or volcanic host rock; if it has been sugar-acid treated, this must be stated in the 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 Matrix 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 Matrix OpalIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of Matrix OpalThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing Matrix OpalCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of Matrix OpalEach value with its source and check date
- Matrix Opal 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 Matrix OpalThe listing name to use; what must be disclosed before sale
- Standard clauses that define Matrix 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
Matrix opal is material in which opal appears as specks, veinlets or impregnations scattered through a sedimentary or volcanic host rock, so that finished stones frequently keep some of the host material. In GIA's account of boulder opal, fragments of the surrounding rock, termed matrix, form part of the finished gem; GIA observations show that opal mineralisation in host rock is highly irregular—occurring as veinlets or veins, clusters or dendritic nests, impregnations, or breccia 'cement'. Note that 'matrix' carries at least two senses in the authoritative sources: fragments of host rock incorporated into a finished boulder opal, and the homogeneous opal bands (differing in colour, transparency or play-of-color) that separate the columnar 'digit' opal, whose presence can aid identification of natural opal. No authoritative definition of the commercial variety name 'matrix opal' has been found, so that identification is graded C and flagged in the limitations.
Scope: Used to describe material in which opal occurs as spots/veinlets/disseminations in sedimentary or volcanic host rock, with the finished piece possibly retaining the host rock; "matrix opal" as a trade variety name lacks an authoritative definition, and the related definition is grade C.
Sources GIA Opal Description · G&G Winter 2023 · G&G Fall 2013
Where it forms
Sedimentary host rock: silica precipitates in cracks and between layers to form opal.
Sources GIA Opal Description
Volcanic or volcaniclastic host rock (e.g. Slovak andesite; weathered Ethiopian ignimbrite): opal occurs as veinlets, impregnations or breccia cement.
Sources G&G Winter 2023
How it forms, step by step
Silica-bearing fluids migrate and precipitate within cracks, layers or cavities in the host rock.
Sources G&G Winter 2023
Within the host rock the silica is distributed very irregularly, forming clusters or dendritic nests, veinlets or veins, breccia 'cement', and impregnations.
Sources G&G Winter 2023
During development of columnar digit opal, homogeneous opal bands of different color, transparency or play-of-color may precipitate between the columns, forming the matrix.
Sources G&G Fall 2013
During cutting, fragments of the host rock (matrix) may be retained as part of the finished gem (as in boulder opal).
Sources GIA Opal Description
Link to appearance
Opal flashes are disseminated as specks or veinlets across the host-rock background, and the finished gem often shows host rock; the inter-column matrix can itself be homogeneous opal differing in color, transparency or play-of-color from the columns.
Sources G&G Fall 2013
Timescale
The cited sources give no numeric age or absolute timescale for matrix opal or for opal mineralization in host rock.
Sources G&G Fall 2013
Related base materials
- Opal (hydrated amorphous silica): variety-of | Matrix opal is a mode of occurrence of opal in which opal is dispersed as specks and veinlets through the host rock (matrix)
- Host rock / matrix: hosted-in | The opal is hosted in sedimentary or volcanic rock, and finished pieces may retain part of the host rock
Supporting findings
Opal mineralization in host rock is extremely irregular, occurring as clusters or dendritic nests, veinlets or veins, breccia 'cement', and impregnations.
Evidence grade AScope: This observation comes from a field report on the Slovak Červenica-Dubník andesite locality; other localities require separate verification.
Sources G&G Winter 2023
Between columnar digit opal there can be homogeneous opal bands (matrix) that differ in color, transparency or play-of-color.
Evidence grade AScope: Describes interstitial filling between digit columns in opals such as those from Ethiopia; it is not identical to the trade variety name 'matrix opal'.
Sources G&G Fall 2013
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
North America
- Honduras
Sources Mindat: Opal
Oceania
- Andamooka, South Australia, AustraliaThe source notes this matrix opal is commonly carbon-impregnated.
Sources Gems & Gemology Summer 1991
- Yowah, Queensland, Australia
Sources Mindat: Opal
- Koroit opal field, Queensland, Australia
Sources Mindat: Opal
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
Where matrix opal carries play-of-color, it follows the same diffraction mechanism as precious opal — orderly arrays of nanoscale silica spheres diffract white light into angle-dependent spectral hues — whereas the matrix between such patches (homogeneous opal bands or host rock) is usually disordered common opal; diffuse scattering from its nanospheres renders it milky or hazy, and no play-of-color emerges.
Evidence grade AScope: The mechanism holds that 'matrix' is typically disordered opal or host rock and produces no play-of-color; it does not establish locality, natural origin, or treatment (for example sugar-acid treatment) of any particular stone.
In opal that develops columnar (digit) structure, the columns are play-of-color patches while the material between them is a homogeneous band differing in colour, transparency, or play-of-color; the flashes are confined to the columns of ordered spheres, and the intervening matrix holds no regular grating of its own.
Evidence grade AScope: The observation comes from studies of digit-structured opal such as Ethiopian material and describes the optical contrast between columns and intervening matrix; it is not equivalent to the trade variety name 'matrix opal' and does not establish locality, natural origin, or treatment.
Sources G&G Fall 2013
How it is identified
Matrix opal is often dyed or otherwise treated to deepen its look, and such treatment is not reliably seen by eye; appearance does not prove naturalness or treatment state either. Deciding whether a specimen is natural, treated or imitation/composite material requires laboratory measurement of gemological properties and composition. The conclusion should be issued by a qualified gem laboratory.
Evidence grade AScope: Applies where natural, treated and imitation opal must be distinguished; no self-administered criteria are given.
Other research findings
A finished boulder opal can include fragments of the surrounding rock, called matrix, as part of the gem.
Evidence grade AScope: This statement concerns the composition of a finished boulder opal; whether host rock is retained depends on cutting.
Sources GIA Opal Description
The trade variety name 'matrix opal' has no authoritative definition in the cited sources; in the sources 'matrix' denotes at least host-rock fragments in boulder opal and the homogeneous opal between digit columns, whose presence can help identify natural opal.
Evidence grade CScope: Defines the nature and usage of the name, graded C; specific material must be identified case by case.
Sources GIA Opal Description · G&G Fall 2013
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The trade name 'matrix opal' lacks an authoritative definition; the identification here is graded C.
- 'Matrix' has at least two senses in the sources (host-rock fragments in boulder opal; homogeneous opal between digit columns) and the two must not be conflated.
- The host-rock distribution description comes from a Slovak locality field report and cannot be generalized to all deposits.
- The cited sources give no numeric age or absolute timescale.
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
- Matrix Opal (state any treatment)
IMA Mineral List 2026-07 “Opal” · CIBJO Gemmological Laboratories Book 2024 §7.2.1.143 “Matrix 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)
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
Matrix Opal is Opal specks or veins disseminated in sedimentary or volcanic host rock; use "Matrix Opal (state any treatment)" for listings, and disclose any known treatments.
Evidence
- CIBJO · 7.2.1.143
What this means for you
Before buying, check the recommended listing name "Matrix Opal (state any treatment)" 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 Matrix Opal, is set out in full under care on the Opal entry.
Care
Matrix 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
- dyeing
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Matrix Opal, p.64; §6.2 k (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Matrix Opal — care (special care): sugar-solution infilling in an acid bath to darken the background and set off the play-of-colour: special care (SC); avoid repolishing.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- dyeing
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.XII, Gemstone Information Chart, Opal Matrix D, 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
ChemicalsOn care of Matrix Opal, the CIBJO (World Jewellery Confederation) Blue Book, Official Gemstone Book 2022, registers that for matrix opal whose status is treated, and only where dyed, treatments with dye, oil, resin, wax or plastic are not permanent, so keep it away from all solvents (including dish-washing liquids), chemicals and heat. The 17th edition of the American Gem Trade Association (AGTA) Gemstone Information Manual registers that for matrix opal whose status is treated, and only where dyed, if it has been filled with a sugar solution in an acid bath to darken the background and set off the play-of-colour, it needs special care (marked SC), and repolishing should be avoided. General careGeneral care that applies to all gemstones, and the full table of special-care letters, are in the general care part of the material entry index page; the Gemological Institute of America (GIA) care and cleaning advice for the whole group is given in full in the care part 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 |
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 | — | — |
| Dyeing | — | — | Treatment | — | — |
| Coating | — | — | Treatment | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: 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
The name register below lists one name for Matrix Opal in a non-Latin script: 1 with no restriction recorded on use as a name.
Recommended listing nameThe suggested listing name for Matrix Opal is Matrix Opal (treatment stated). Institution usageOn authority wording for the English name Matrix Opal, CIBJO has Matrix Opal on record (CIBJO Gemmological Laboratories Book 2024); the FTC text on file has been checked and has no wording for this name; GIA and Gem-A are unchecked. Bodies without a record show the entry's own English name, which does not represent their position. Japanese namesThe GSJ (Japan) formal name is given in Japanese, but the GSJ wording for this name is not yet verified by this site, and the entry's own Japanese name is shown. Candidate search termsThe JJA/AGL gem name handbook 2025 p.9 also records a Japanese name meaning “opal with host rock”, used only as a candidate search term. Chinese standard nameThe corresponding national-standard name is opal (GB/T 16552—2017 Table A.2); the name Matrix Opal itself is not listed in the original. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Matrix Opal) and Japanese.
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) | ||||
| 母岩付オパールJapanese | transliteration | search candidate only | no restriction recorded | JJA/AGL Gemstone Nomenclature 2025 p.9 |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- マトリックスオパール (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)
- 欧泊 (GB/T 16552—2017 Table A.2)
- Mineralogical name
- Opal specks or veins disseminated in sedimentary or volcanic host rock
Four-language names
- 简体中文
- 基质欧泊
- 繁體中文
- 基質歐泊
- English
- Matrix Opal
- 日本語
- マトリックスオパール
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 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 |
|---|---|---|---|---|
| Matrix Opal | Opal | an untreated tier is listed | play of colour; with host rock |
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
The registered phase composition of Matrix Opal is opal. Recorded for opal as a whole class: structure (overall) amorphous; no cleavage; no birefringence; optic character isotropic, with anomalous extinction commonly seen in fire opal; the play-of-colour optical effect may be seen; the cat's-eye optical effect may be seen but is rare. For opal as a whole class, density 1.25–2.23 g/cm³ is converted from the cited clause value of 2.15 with tolerances of +0.08 and −0.90; refractive index 1.37–1.47 is converted from the clause value of 1.450 with tolerances of +0.020 and −0.080, and the clause also gives finer bands, with the overall value registered. Mohs hardness is 5–6.5; the cited clause covers the whole species, of which Matrix Opal is only one variety. For opal as a whole class, pleochroism is none (treatment state: untreated) and the quality factor (lustre) is vitreous to resinous (treatment state: untreated). Stability is registered as brittle, porous, liable to crack on losing water, sensitive to sudden temperature changes and not to be cleaned ultrasonically, with treatment state untreated.
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 Matrix 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 Matrix Opal (how to read class-level values).
Definition
Matrix Opal — composition (phase): opal
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Matrix 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
Matrix 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
Matrix 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
Matrix 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
Physical properties
Matrix 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
Matrix 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
Matrix 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
Matrix 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
Matrix 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
optical effect (play of colour)2 sources compared
Matrix 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
Matrix 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
Matrix 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
- CIBJO definitions
- play of colour, chatoyancy
Quality factors
Matrix 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
Related CIBJO terms
- Sugar/acid treatment
Matrix opals treated in a solution of acidified glucose-lactose with a few drops of concentrated sulfuric acid, then heated until the sugar solution solidifies. The gemstone is then immersed in sulfuric acid and heated to reduce the sugar to black carbon. See “dyeing” within the chart of clause 4.2.5.2.
CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §5.78, p.28
Definitions are quoted verbatim from the cited CIBJO Blue Book; […] marks an excerpt, and the full definition is at the cited clause.
Testing and market
The CIBJO laboratory protocol covers Matrix 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
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Matrix Opal is defined directly in the CIBJO Gemmological Laboratories Book 2024 under the term Matrix opal: mineral species opal, rock sedimentary or volcanic, trade name Matrix opal, with the CIBJO wording quoted in full under Clause-level definitions on this page. The cross-check result is defined directly by CIBJO, with no English name of the same name found directly in the GB/T annex.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Matrix opal | 7.2.1.143 | Thin seams or spots of opal with play-of-colour scattered throughout matrix (sedimentary or volcanic rock) | 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.
- 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 (Matrix 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) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Matrix 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.