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Natural inorganic gem materials · Commercial / trade name · Natural identity; treatment status unknown
Black Diamond (treated)
Also known asBlack Diamond (conditional name)
Diamond treated to look black: the Japanese JJA/AGL disclosure list attributes its black colour to carbonization by heating or to irradiation. It is not carbonado, a naturally black polycrystalline aggregate. 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 Black Diamond (treated) 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 Black Diamond (treated)Identification points from the research literature
- Treatments and enhancements of Black Diamond (treated)2 registered treatments: status, stability, how common they are and identification leads
- Black Diamond (treated) in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Listing and disclosing Black Diamond (treated)The listing name to use; what must be disclosed before sale
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
A treated black diamond is simply a natural diamond whose black appearance has been brought about by artificial treatment; it is not a synthetic product. Colour in natural fancy black diamonds has a complex origin, tied to dark inclusions (graphite, or the iron oxides hematite and magnetite), radiation stains, or a very high concentration of absorption defects. Independently of that, black can also be produced by any of several treatments — heating at high temperature in vacuum, for example, or heavy irradiation. In identity terms it is a treated natural diamond, and its treatment must be disclosed when named and sold.
Scope: Applies to diamonds that use natural diamond as the parent material and have been treated to appear black; not applicable to black diamonds of natural origin, nor to synthetic (laboratory-grown) diamonds.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Where it forms
Treatment environment: a high-temperature vacuum furnace (heating under vacuum to blacken the diamond) or a controlled irradiation facility (heavy irradiation treatment). The treatment itself is not a natural process.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Parent origin (not this treated product's own setting): the natural diamond used as the parent formed at high pressure and temperature in Earth's mantle; this describes the parent material only, and the treatment involves no natural formation.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
How it forms, step by step
Select the parent material: usually a natural diamond carrying dark inclusions (graphite, iron oxides), radiation stains, or a very high concentration of absorption defects.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Treatment route one: heat the diamond at high temperature under vacuum to turn it black.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Treatment route two (alternative): apply heavy irradiation treatment to create the black color.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Disclosure and naming: identify it as a treated diamond and market it under CIBJO treatment-disclosure rules.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Link to appearance
Treated black diamonds appear black, from opaque to semi-transparent; the black color comes from artificial treatment rather than a natural cause, so appearance alone cannot indicate a natural black diamond.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Timescale
The sources state no specific duration for the treatment, nor any historical date or start time for black-diamond treatment.
Sources G&G Summer 2025 · CIBJO Gemstone Book 2022
Related base materials
- Diamond: Parent material: treated black diamond is natural diamond whose colour has been turned black by artificial treatment; it retains the diamond substance.
Recorded localities
This is a manufactured, assembled or treated product that contains natural material. No locality is given for the finished product; see the parent material's entry for where the natural component is recorded.
Causes of colour and optical effects
For the natural black diamond serving as parent material the colour has a complicated origin: dark-coloured inclusions (graphite, or iron oxides — hematite, magnetite), radiation stains, or a very high concentration of absorption defects.
Evidence grade AScope: Applies to the color cause of the natural black diamond (parent); not to treatment-induced black color.
How it is identified
A treated black diamond (for example colour-changed by irradiation or HPHT) often leaves no microscopic evidence, and its appearance cannot show whether the colour is treatment-induced. Identification rests on measurable properties and the division of labour between instruments: magnification of inclusions, colour zoning and graining (growth striations); ultraviolet fluorescence for the fluorescence pattern; spectroscopy (a 415 nm 'Cape' line proving natural origin, nickel-related lines indicating synthetic); and strain patterns under crossed polarizers; advanced methods include cathodoluminescence, EDXRF chemical analysis, infrared spectroscopy and time-gated luminescence imaging. Limitations: some colour treatments are not visible under the microscope and depend on laboratory instruments, so the conclusion must be issued by an accredited gemological laboratory through testing.
Evidence grade AScope: Identification and separation points; testing must be performed by an accredited gemological laboratory, and no self-test thresholds are given.
Other research findings
A treated black diamond can be produced by heating a natural diamond at high temperatures under vacuum to make it black.
Evidence grade AScope: Covers vacuum high-temperature blackening treatment of diamond; not synthesis or natural formation.
The black color in such diamonds can also be created by heavy irradiation treatment.
Evidence grade AScope: Covers irradiation blackening treatment; not synthesis or natural formation.
A treated black diamond is a treated natural diamond rather than a synthetic product; CIBJO requires disclosure of treatment and non-misleading naming.
Evidence grade AScope: Covers the identity and disclosure of treated black diamond; not specific treatment processes.
Sources CIBJO Gemstone Book 2022
A sizeable proportion of the black diamonds on the market have been treated: among those GIA examined, more than a third had been treated.
Evidence grade AScope: A statement about the share of treated black diamonds examined; not a price or value judgment.
The treatment changes only the diamond's appearance (color), not its intrinsic composition as diamond; CIBJO classifies such materials as treated gemstones.
Evidence grade AScope: Covers the definition that treatment changes appearance but not composition; not synthetic materials.
Sources CIBJO Gemstone Book 2022
Treated black diamond resembles natural fancy black diamond in appearance, so quality evaluation must first separate the origin of colour: whether the colour is natural or produced by irradiation, high pressure–high temperature or other treatment, and any treatment must be disclosed. In quality terms, black or dark fancy colour diamonds are usually dominated by colour (hue, tone, saturation) and uniformity, with clarity and cut weighted differently from colourless diamond; surface lustre and the quality of workmanship also enter the assessment. Evaluation and disclosure must distinguish it from natural fancy colour diamond, and the specific grade and origin of colour must be issued by an accredited laboratory on the specific specimen.
Evidence grade BScope: This describes the diamond quality factors the market generally prizes; it is not a grade for any specific specimen and is neither price nor investment advice; the 4Cs system applies to diamonds and is not transferable to coloured stones; a specimen's grades must be issued by an accredited laboratory.
Sources GIA Fancy Color Diamond Quality Factors · GIA Diamond Quality Factors
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The available sources do not quantify the stability or durability of treated black diamonds (whether the color fades, needs special care, or is reversible), so no such claim is made.
- The sources do not address the value or investment attributes of treated black diamonds, so no price or investment judgment is made.
- The sources give no specific duration or temperature parameters for the treatment.
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
- Treated black diamond (state the treatment)
GB/T 16552—2017 5.4.2.2 a) · IMA Mineral List 2026-07 “Diamond”
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
Under the naming rules of the Chinese standard (GB/T 16552—2017 §5.4.2.2 a)), Black Diamond (treated) takes a composed Chinese name that differs from its common trade name; use "Treated black diamond (state the treatment)" for listings.
Evidence
- GB/T · 5.4.2.2 a)
What this means for you
Before buying, check the recommended listing name "Treated black diamond (state the treatment)" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- This entry's exact material identity is not fully settled.
- See “Disclosure and cautions” above
- Last reviewed
- 2026-09-26
Trade-name ruling
- Trade name rather than a mineralogical species name.
- Laboratory identification required before the name is used.
- Suggested listing name
- Treated black diamond (state the treatment)
Care and wear
No care facts are recorded for this entry itself. Its parent material has care records: see Diamond.
Treatments and identification leads
Registered treatmentsThe treatments registered for Black Diamond (treated) are irradiation and heating. Values not givenBoth irradiation and heating have status treated; their stability and prevalence are not given by the cited source and are registered as "—". Identification cluesThe identification lead for irradiation is that immersion microscopy shows colour concentrated at the surface, becoming lighter from the surface layer inwards, and a conclusion usually requires combined infrared, near-infrared, UV-visible and photoluminescence spectral data. The identification lead for heating is that, if treated at high temperature and low pressure, magnification shows graphitized feathers. The source for both irradiation and heating is GB/T 16553—2017.
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| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| irradiationStatus: treated | — | — | — | — | See identification leads |
| heatingStatus: treated | — | — | — | — | See identification leads |
Where each treatment acts (schematics): Irradiated · Heated / Heat-treated
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16553—2017
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
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Black Diamond (treated), the name register records "Black Diamond", for which no restriction on use as a name is recorded.
Standard and listing namesUnder the GB/T 16552—2017 naming rules, the name built for Black Diamond (treated) is diamond (treated); it is not listed as such in the original, and the basic name is diamond. The suggested listing name is diamond (treated). Trade and mineralogical namesThe trade name/synonym is Black Diamond, a market name that is matched to Black Diamond (treated) only once the conditions are confirmed. Names in four languagesFour-language names are given in Simplified Chinese, Traditional Chinese, English (Black Diamond (treated)) and Japanese. Institution usageOn authority wording, the FTC and CIBJO texts on file have no wording for Black Diamond (treated) (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 entry has its own Japanese name, and the wording of Japan's GSJ for this name is not yet verified by this site. Trade and mineralogical namesThe mineralogical name describes diamond coloured black by treatment, through graphitisation by heating or through irradiation.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
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| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| Black DiamondEnglish | market name | matched only once the condition is confirmed | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- ブラック・ダイヤモンド (not yet checked for this body — the entry's own Japanese name is shown)
- Name built by the GB/T naming rules (not listed as such)
- 钻石（处理） (GB/T 16552—2017 §5.4.2.2 a); basic name 钻石)
- Mineralogical name
- Diamond coloured black by treatment (graphitisation by heating, or irradiation)
- Trade names and synonyms
- Black Diamond (market name; conditional name)
Four-language names
- 简体中文
- 黑钻石（处理）
- 繁體中文
- 黑鑽石（處理）
- English
- Black Diamond (treated)
- 日本語
- ブラック・ダイヤモンド
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
- Commercial / trade name
- Mineral chemical class
- Native elements
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
The registered material facts for Black Diamond (treated) are identification leads for treated stones. In irradiated treated Black Diamond, colour under the microscope with immersion is concentrated in the surface layer and fades inward, and a conclusion usually needs infrared, near-infrared, UV-visible and photoluminescence spectral data together. In heat-treated Black Diamond, where the treatment is high-temperature low-pressure, magnification shows graphitised feathers. The conclusions for both irradiation and heating assume the treatment state “treated”, and the cited GB/T 16553—2017 can be followed for Black Diamond (treated) as a reference only and does not govern it directly.
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”.
How far testing can go
Treated Black Diamond that has undergone irradiation can be identified by the following features: Under the microscope with immersion, colour is concentrated at the surface and fades inward; a conclusion usually needs infrared, near-infrared, UV-visible and photoluminescence data together.
GB/T 16553—2017
- Treatment state
- treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- irradiation
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (irradiation) (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Treated Black Diamond that has undergone heating can be identified by the following features: If the diamond has been treated at high temperature and low pressure, magnification shows feather-like fractures that have turned to graphite.
GB/T 16553—2017
- Treatment state
- treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- heating
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (HPHT treatment) (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.
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.
- eCFR (United States). 16 CFR Part 23 — Guides for the Jewelry, Precious Metals, and Pewter Industries.
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 Diamond on this site: 4 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Black Diamond (treated)) is marked.
- Diamond
Sub-entries (3)
- Black Diamond (treated)
- Fancy Color Diamond
- Synthetic Diamond (Synthetic product)
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| 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 Black Diamond (treated) 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. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.