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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Carbonado
A black polycrystalline diamond aggregate whose mineral species is diamond, but it is not a synonym for single-crystal diamond; the name does not appear anywhere in GB/T 16552-2017. 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 Carbonado forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify CarbonadoIdentification points from the research literature
- Carbonado 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 CarbonadoThe listing name to use; what must be disclosed before sale
- Standard clauses that define CarbonadoWhich 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
Carbonado, or black diamond, is a variety/aggregate of diamond rather than a mineral species in its own right; its parent substance is diamond, i.e. carbon. This entry therefore summarises that parent: diamond is unique among gems in being composed of a single element, carbon at roughly 99.95 percent, and it crystallises where temperature and pressure are high, an environment encountered only across a narrow depth interval—about 100 miles down—below the Earth's surface. NOTE: the cited sources cover only diamond (the parent); they say nothing about carbonado's polycrystalline texture, its limited localities or the cause of its colour, so no such detail is asserted, in order to avoid speculation.
Scope: Applies to the identity definition of carbonado as a diamond aggregate/variety and to an overview of the genesis of its parent material diamond; because the cited sources do not cover carbonado itself, no specific assertions are made on its polycrystalline structure, localities or colour origin.
Sources GIA Diamond Description
Where it forms
Parent-diamond setting: at about 100 miles depth beneath Earth's surface, under high temperature and pressure that exists only within that depth range (a parent-material fact, not specific to carbonado).
Sources GIA Diamond Description
NOTE: the cited sources do not describe carbonado's own setting or localities.
Sources GIA Diamond Description
How it forms, step by step
The parent diamond forms at about 100 miles depth under high temperature and pressure (a parent-material fact).
Sources GIA Diamond Description
By material classification, carbonado is grouped as an aggregate/variety of diamond.
Sources GIA Diamond Description
NOTE: the cited sources do not describe the specific formation steps of this aggregate/variety, so no process is invented.
Sources GIA Diamond Description
Link to appearance
NOTE: the cited sources do not describe carbonado's own color or appearance; no appearance claim is made.
Sources GIA Diamond Description
Timescale
The sources state no absolute geological timescale for the formation of carbonado (or of its parent diamond).
Sources GIA Diamond Description
Related base materials
- Diamond: Carbonado is a polycrystalline aggregate/variety of diamond (carbon); its parent material is diamond, and it is not an independent mineral species.
Supporting findings
Its parent substance, diamond, crystallizes where temperature and pressure are high, an environment found only across a limited depth interval—some 100 miles down—below the surface of the Earth; its crystal structure is isometric.
Evidence grade AScope: This is a parent-diamond formation fact, not unique to carbonado (the aggregate).
Sources GIA Diamond Description
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Central African RepublicThe article states carbonado is found only in Brazil and the Central African Republic (2017)
Sources Gems & Gemology Summer 2017
South America
- Chapada Diamantina, Bahia, BrazilThe article states carbonado is found only in Brazil and the Central African Republic (2017)
Sources Gems & Gemology Summer 2017
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 the origin determination guide and the overview of recorded localities.
How it is identified
Many diamonds show no diagnostic internal features, so a bench inspection cannot establish whether the stone is natural, treated or laboratory-grown; advanced testing is needed. Laboratory work begins with magnification, looking for diagnostic mineral inclusions, possibly magnetic metallic flux particles, or tubes left by laser drilling, then weighs ultraviolet fluorescence and luminescence behaviour and visible-range spectral features together with instrumental methods such as infrared spectroscopy and surface luminescence imaging to separate natural, synthetic and treated diamonds. Because a single feature can be ambiguous, the identification should be issued by a qualified gem laboratory.
Evidence grade AScope: Applies where natural, treated and laboratory-grown diamonds must be distinguished; no self-administered criteria are given.
Sources G&G Winter 2018 · G&G Winter 1995 · G&G Summer 2020 +1
- Inclusions in Natural, Synthetic, and Treated Diamond (Gems & Gemology, Winter 2018)
- A Chart for the Separation of Natural and Synthetic Diamonds (Gems & Gemology, Winter 1995)
- Separation of Natural from Laboratory-Grown Diamond Using Time-Gated Luminescence Imaging (Gems & Gemology, Summer 2020, Vol. 56, No. 2)
- Laboratory-Grown Diamonds: An Update on Identification and Products Evaluated at GIA (Gems & Gemology, Summer 2024, Vol. 60, No. 2)
Other research findings
Carbonado (black diamond) is classified as an aggregate/variety of diamond rather than an independent mineral species, and its parent material is diamond (carbon).
Evidence grade BScope: Classification follows the material catalogue and parent relationship; the cited source does not describe its polycrystalline texture.
Sources GIA Diamond Description
Its parent substance, diamond, is unique among gems in consisting of just one chemical element, carbon, at roughly 99.95 percent; whatever trace elements are present make up the remaining 0.05 percent.
Evidence grade AScope: This is a parent-diamond composition fact, not unique to carbonado (the aggregate); it must not be presented as carbonado-specific.
Sources GIA Diamond Description
Carbonado is an opaque, polycrystalline aggregate of diamond, and its quality is not assessed on the colourless-to-light-yellow D-to-Z colour and clarity system. For diamond generally, opaque black falls within fancy-colour description; GIA notes that a diamond's opaque black colour can be caused by dark inclusions or, more commonly, by colour treatment. The origin (natural, treated, etc.) and quality characteristics of opaque diamond must therefore be determined by an accredited laboratory; the 4Cs describe diamonds and do not apply to coloured gemstones.
Evidence grade BScope: Quality factors describe which characteristics the market generally prizes; they are not a grade for any specific specimen and are neither price nor investment advice. The 4Cs system applies to diamonds and is not transferable to coloured gemstones.
Sources GIA Fancy Color Diamond Quality Factors · GIA Diamond Quality Factors
The GIA sources cited here provide no size superlative for carbonado, the polycrystalline diamond aggregate. The 1988 article's faceted-diamond superlative, Cullinan I at 530.20 ct, is a single-crystal colourless stone, not carbonado.
Evidence grade AScope: States that the sources give no carbonado record and that the 1988 article's faceted-diamond superlative is a single-crystal colourless stone. Records change over time; limited to the source year (1988).
Sources G&G Spring 1988
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The cited sources do not address carbonado itself and do not describe its polycrystalline structure, restricted localities (e.g. Central Africa, Brazil), or color origin, so no such detail is asserted; only parent-diamond facts and the material classification are stated.
- Parent-diamond facts are kept distinct from the aggregate/variety classification, and parent facts are not passed off as carbonado-specific.
- The sources state no absolute geological timescale for the formation of carbonado or its parent diamond.
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
- Carbonado
IMA Mineral List 2026-07 “Diamond” · CIBJO Gemmological Laboratories Book 2024 §7.2.1.40 “Carbonado”
Construction or treatment status
Natural identity; treatment status unknown
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
Carbonado is Black polycrystalline diamond aggregate; use "Carbonado" for listings, and disclose any known treatments.
Evidence
- CIBJO · 7.2.1.40
What this means for you
Before buying, check the recommended listing name "Carbonado" 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
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesGB/T 16552—2017 does not list Carbonado; the corresponding item in Table A.1 is diamond, and the name itself is not listed in the standard. The suggested listing name is Carbonado. Institution usageOf GIA, FTC, CIBJO and Gem-A, CIBJO records Carbonado (CIBJO Gemmological Laboratories Book 2024); the FTC text on file has no wording for this name (checked); GIA and Gem-A are unchecked; bodies without a recorded wording show the entry's own English name, which does not represent their position. Japanese namesThe Japanese name shown is the entry's own; the wording used by the GSJ (Japan) for this name is not yet verified by this site. Trade and mineralogical namesThe mineralogical name is a black polycrystalline diamond aggregate. Names in four languagesNames are registered in four languages: Simplified Chinese, Traditional Chinese, English (Carbonado) and Japanese.
- GSJ (Japan) formal name
- カルボナード／黒色ダイヤ (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)
- 钻石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Black polycrystalline diamond aggregate
Four-language names
- 简体中文
- 黑金刚石
- 繁體中文
- 黑金剛石
- English
- Carbonado
- 日本語
- カルボナード／黒色ダイヤ
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Native-element minerals
- Identity tier
- Mineral / gemstone variety
- Mineral chemical class
- Native elements
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
Registered material facts for Carbonado: transparency is opaque; body colour is black, grey or brown, untreated. On body colour, a site note points out that in Chapter 7 of the CIBJO Gemmological Laboratories Book the colour descriptions for entries such as nuummite, hematite and morion also mention black or blackish colours.
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”.
Optical
Carbonado — transparency: opaque.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Carbonado — body colour: Black, grey or brown.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Nuummite, Hematite, Morion / very dark Smoky Quartz and other entries also name black or a blackish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- 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.
Clause-level definitions
Carbonado has a clause-level definition in the CIBJO Gemmological Laboratories Book 2024 under the term Carbonado. The listed clause gives the mineral species as diamond and graphite and the mineral/gem variety as Carbonado, noting that the CIBJO wording is quoted in full under Clause-level definitions on this page. The cross-check result is a direct CIBJO definition, with no identically named English entry found in the GB/T annex.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Carbonado | 7.2.1.40 | Mixture of diamond, graphite and amorphous carbon. Black, grey or brown, opaque | 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.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Native-element minerals | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Carbonado 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.