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Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown

Diamond

A mineral species composed of carbon, listed as “diamond” in Table A.1 of GB/T 16552-2017; clause 5.1.2.1 b) states that origin plays no part in naming. 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.

Edited by RalphReviewed by JuneLast updated 2026-10-12Who maintains this page

FAQCare and wear

Questions people ask about Diamond

Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.

Q1What separates a natural diamond from a lab-grown or treated one?

Not reliably by eye: natural, laboratory-grown and treated diamonds can be hard to tell apart, and stones without diagnostic inclusions need advanced testing.G&G Winter 2018A laboratory typically starts with routine observation, then combines ultraviolet and deep-ultraviolet fluorescence imaging, infrared and photoluminescence spectroscopy and screening instruments to decide whether a stone is natural, synthetic or treated.G&G Winter 2018In the infrared spectrum, absorption bands from carbon–carbon bond vibration at 2 030 cm⁻¹, 2 160 cm⁻¹ and 2 350 cm⁻¹ are what let diamond be told apart from its imitations.GB/T 16553—2017Its Raman peak at 1 332 cm⁻¹ reliably separates opaque black diamond from imitations such as black synthetic moissanite.GB/T 16553—2017Diamond is harder than any of its imitations, and synthetic moissanite is doubly refractive, so its back facets look doubled.GIA 4Cs blog (2016)A standard thermal probe cannot separate diamond from synthetic moissanite, because both react as diamond.Gems & Gemology 1997 (Nassau et al.)Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer

Q2What colours do diamonds come in, and what causes the colour?

Diamond runs from colourless to yellow or brown, and also occurs in pink (rarely red), green, blue, orange, grey and black.CIBJO Gemmological Laboratories Book 2024Diamond is usually around 99.95 percent carbon, and some of the trace elements making up the remaining 0.05 percent may influence its colour.GIA Diamond DescriptionGB/T 16553—2017 sorts diamond colours into a colourless to light yellow (brown, grey) series and a coloured series that includes yellow, brown, grey and light to dark blue, green, orange, pinkish red, red, purplish red and black.GB/T 16553—2017

Q3Can a diamond chip or break with everyday wear?

Yes, it can: diamond rates 10 on the Mohs scale and only a diamond can scratch a diamond, but it still has cleavage directions, so a hard blow can cleave it and pointed corners can chip.GIA Gem Encyclopedia (care guide)A split can happen during setting as well as in wear, and shapes with points are often set with prongs guarding the corners.GIA Gem Encyclopedia (care guide)Diamond can scratch any precious metal used in settings, so a stone that has worked loose can wear through a prong over time.GIA Gem Encyclopedia (care guide)Prong, bezel, flush, channel and pavé settings are all rated relatively safe, though heavily included stones, or those with feathers or fractures near the girdle, need extra care.Gems & Gemology 1987 (Martin)

Q4Are diamonds treated, and does the treatment last?

Yes: diamonds can be irradiated and/or heated to fancy colours, and these need only normal care except treated green stones, which should not be heated because the colour may change.AGTA Gemstone Information Manual, 17th ed.Colourless to faint yellow diamonds that have been HPHT-treated for colour or clarity need normal care.AGTA Gemstone Information Manual, 17th ed.Diamonds laser-drilled to improve their appearance also need normal care.AGTA Gemstone Information Manual, 17th ed.Diamonds with a hardened filler in surface cavities or fractures need special care, because recutting or extreme heat can remove the filler.AGTA Gemstone Information Manual, 17th ed.On coated diamonds, recutting, steaming and ultrasonic cleaning can spoil the colour and look, and on coated colourless to faint yellow stones alcohol sometimes can too.AGTA Gemstone Information Manual, 17th ed.

Q5How should you clean a diamond, and can heat or chemicals damage it?

Lint-free cloths, commercial jewellery cleaners and household detergents are safe; powdered abrasive cleansers, ultrasonic and steam cleaners are not for home use, as ultrasonic and steam cleaning can loosen stones in their settings.GIA Gem Encyclopedia (care guide)Another source rates ultrasonic and steam cleaning as relatively safe for diamond, with care needed for stones that have feathers or many inclusions.Gems & Gemology 1987 (Martin)Coated diamonds are an exception: steaming and ultrasonic cleaning can spoil their colour and look.AGTA Gemstone Information Manual, 17th ed.Almost no acid harms diamond; the real threat is a sudden, extreme temperature change, which can start or spread cracks, and diamond burns at about 850 °C.GIA Gem Encyclopedia (care guide)

Q6Is diamond really just carbon, like graphite?

Yes: diamond is a mineral species made of a single element, carbon; graphite is also composed only of carbon, but because their formation and crystal structure differ, the two have very different properties.GIA Diamond DescriptionDiamond is the only gemstone composed of a single element, usually around 99.95 percent carbon.GIA Diamond DescriptionIts isometric structure bonds the carbon atoms essentially the same way in every direction, and compared with graphite this gives diamond extraordinary hardness.GIA Diamond Description

Q7How do natural diamonds form?

Natural diamond forms where temperatures and pressures are high, conditions found only in a particular depth band roughly 100 miles below Earth's surface.GIA Diamond DescriptionThere, carbon bonds into an isometric structure.GIA Diamond DescriptionThe common rough crystal shape is the octahedron, and nearly perfect, transparent crystals are called glassies.GIA Diamond DescriptionThe source states no absolute geological timescale for diamond formation.GIA Diamond Description

Q8What decides a diamond's quality?

Diamond quality is conventionally described by four factors, the 4Cs: carat weight, colour, clarity and cut.GIA Diamond Quality Factors · G&G Winter 1994Colour is graded on GIA's D-to-Z scale, where the nearer a stone comes to colourless the rarer it is; clarity concerns how free it is of inclusions and blemishes; and cut governs how it handles light.GIA Diamond Quality Factors · G&G Winter 1994Fancy colour diamonds outside the D-to-Z range use a separate colour vocabulary of hue, tone and saturation.GIA Diamond Quality Factors · G&G Winter 1994

Q9Is a lab-grown diamond a real diamond?

Under the US FTC Jewelry Guides, a diamond is a mineral of essentially pure carbon crystallised in the isometric system, and laboratory-created diamonds with essentially the same properties may be called cultured only with a clear and conspicuous disclosure, such as laboratory-grown, that they are not mined.16 CFR Part 23 (US)Naming, disclosure and labelling information on this site is reference material and does not constitute legal advice. Actual labelling duties follow the regulations in force in each jurisdiction and the testing certificates that accompany the goods; verify independently or consult a professional before relying on it.What this page can answer

Q10What does diamond symbolize, and does it have healing powers?

There is no scientific evidence that diamond has healing powers: the UK advertising regulators ASA and CAP state that they have not seen evidence that crystal therapy can treat medical conditions.ASA/CAP guidance (UK)Its recorded cultural role is as the April birthstone: Jewelers of America and Japan's JJA list it for April, and the U.K. National Association of Jewellers lists it as traditional for April.Cultural recordsIt also marks the 60th and 75th wedding anniversaries.GIA Diamond Description

What this page can answer

This page covers

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

Diamond is the sole gemstone composed of a single element: usually around 99.95 percent carbon, with the remaining 0.05 percent present as one or more trace elements, some of which may influence its colour or crystal shape. Diamond forms where temperatures and pressures are high — conditions found only in a particular depth band, roughly 100 miles below Earth's surface. Its crystal structure is isometric, so the carbon atoms are bonded essentially the same way in every direction. Compared with graphite, composed only of carbon but formed differently and with a different structure, this gives diamond extraordinary hardness. Rough gem-quality diamond most often takes the form of an octahedron.

Scope: Covers an overview of the origin and identification of diamond as a single-element (carbon) mineral species; does not address synthetic (laboratory-grown) diamonds or imitations.

Sources GIA Diamond Description

Where it forms

At about 100 miles depth beneath Earth's surface, in the high-temperature/high-pressure regime that exists only within that depth range (a host-material origin, not a processing step)

Sources GIA Diamond Description

How it forms, step by step

  1. At depth of about 100 miles, under high temperature and pressure, carbon bonds into an isometric structure.

    Sources GIA Diamond Description

  2. Diamond forms at about 99.95 percent carbon, with about 0.05 percent trace elements entering the structure.

    Sources GIA Diamond Description

  3. Trace elements can influence the diamond's color or crystal shape.

    Sources GIA Diamond Description

  4. The common rough crystal shape is the octahedron; nearly perfect, transparent crystals are called glassies.

    Sources GIA Diamond Description

Link to appearance

Diamond's composition and isometric crystal structure give it extreme hardness and the highest possible luster of any transparent gemstone (adamantine luster); crystals commonly form octahedra, and fashioned stones show brightness, sparkle, and fire.

Sources GIA Diamond Description

Timescale

The source states no absolute geological timescale for diamond formation.

Sources GIA Diamond Description

Supporting findings

Diamond forms where temperatures and pressures are high — conditions found only in a particular depth band, roughly 100 miles below Earth's surface — and its crystal structure is isometric.

Evidence grade A

Scope: Describes natural diamond formation conditions; not laboratory synthesis.

Sources GIA Diamond Description

Recorded localities

Authoritative sources list the localities below; the list is not exhaustive.

Locality sketch mapLand outlines only; the map does not depict any national or regional boundary. Dots mark approximate positions. Base map: Natural Earth (public domain).

Africa

Asia

North America

South America

Oceania

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.

Where the name comes from

Under the US Federal Trade Commission's Jewelry Guides, a diamond is defined as a mineral consisting essentially of pure carbon crystallised in the isometric system. The Guides do not treat it as unfair or deceptive to call laboratory-created diamonds with essentially the same optical, physical and chemical properties as mined diamonds 'cultured', provided the term is qualified by a clear and conspicuous disclosure, such as 'laboratory-grown', that the product is not a mined stone.

Evidence grade A

Scope: States only what the cited official text says. It does not cover other jurisdictions, later changes or any particular item. Not legal advice.

Sources 16 CFR Part 23 (US)

Human use and museum objects

Nearly every modern birthstone list names diamond as April's birthstone, and it also marks the 60th and 75th wedding anniversaries.

Evidence grade A

Scope: Concerns cultural use, not geological formation.

Sources GIA Diamond Description

Cultural records for this material: Birthstone list.

How it is identified

Diamond, laboratory-grown diamond and treated diamond can be hard to tell apart by eye, and stones lacking diagnostic inclusions demand advanced testing. A laboratory typically begins with routine observation, then combines ultraviolet and deep-ultraviolet fluorescence imaging with infrared and photoluminescence spectroscopy and screening instruments to decide natural, synthetic or treated status; this is work for an accredited laboratory, not for untrained judgement.

Evidence grade A

Scope: Determining natural/synthetic/treated diamond is laboratory testing to be issued by an accredited body; this entry is not self-identification.

Sources G&G Winter 2018

Overall, diamond is harder than any of its imitations. Synthetic moissanite is doubly refractive, so its back facets look doubled and it may appear slightly fuzzy in some directions, unlike diamond.

Evidence grade B

Scope: Describes identification features reported by a laboratory or educational source; it is not a test that a reader can rely on, and any single piece can only be identified by a gemmological laboratory.

Sources GIA 4Cs blog (2016)

A standard thermal probe does not separate diamond from synthetic moissanite, because their thermal inertia ranges overlap and both react as 'diamond'. A dedicated instrument introduced for this purpose was designed to be used only on stones that first test positive for diamond on a thermal probe.

Evidence grade B

Scope: Describes identification features reported by a laboratory or educational source; it is not a test that a reader can rely on, and any single piece can only be identified by a gemmological laboratory.

Sources Gems & Gemology 1997 (Nassau et al.)

Other research findings

Diamond is the sole gemstone composed of a single element, usually around 99.95 percent carbon; the remaining 0.05 percent can comprise one or more trace elements, some of which may influence its colour or crystal shape.

Evidence grade A

Scope: Describes diamond's chemical composition; not synthetic diamond or treatment.

Sources GIA Diamond Description

Diamond is a mineral species made of a single element, carbon; graphite, too, is composed only of carbon, but because its formation and crystal structure differ, the two have very different properties.

Evidence grade A

Scope: Defines diamond's mineral identity and distinguishes it from carbon-only graphite.

Sources GIA Diamond Description

Rough gem-quality diamond most often takes the form of an octahedron; near-perfect transparent crystals are known as glassies; and diamond possesses the highest possible lustre, adamantine.

Evidence grade A

Scope: Describes rough habit and luster; the source gives no detailed optical mechanism for the luster.

Sources GIA Diamond Description

Diamond quality is conventionally described through four factors — carat weight, colour, clarity and cut (the 4Cs). Colour runs on GIA's D-to-Z scale, where the nearer a stone comes to colourless the rarer it is; clarity concerns how free it is of inclusions and blemishes; cut governs how it handles light; and weight is given in metric carats. Together these describe a finished diamond and are how the trade compares one with another. Fancy colour diamonds lying outside the D-to-Z range use a separate colour vocabulary (hue, tone, saturation), unlike colourless stones. The 4Cs describe diamonds and cannot be carried over to coloured gems.

Evidence grade A

Scope: 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 Diamond Quality Factors · G&G Winter 1994

The piece recorded by the cited 1988 GIA article Faceting Large Gemstones as the world's largest faceted diamond is Cullinan I, weighing 530.20 ct; the article in turn credits a 1987 reference (Arem). That figure comes from 1988 literature and may well have been superseded since.

Evidence grade A

Scope: A record statement subject to change; the record comes from 1988 literature and a larger faceted diamond may since have appeared. Distinguish the largest faceted diamond from the largest diamond rough.

Sources G&G Spring 1988

Limits of this research

  • Research status: Formation, occurrence or other material-specific findings found in authoritative sources
  • The source states no absolute geological timescale for diamond formation.
  • The source gives no detailed mechanism for the diamond crystal structure.

Methodology

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
Diamond

GB/T 16552—2017 Table A.1 “Diamond” · IMA Mineral List 2026-07 “Diamond”

Construction or treatment status

Natural identity; treatment status unknown

Treatments recorded for this material: Filled / Fracture-filled, Irradiated, Coated, HPHT treated, Laser-drilled, Heated / Heat-treated

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

Diamond is often subjected to filling, irradiation, coating, HPHT treatment and laser drilling. Under GB/T 16552-2017, filling, irradiation, coating, HPHT treatment and laser drilling count as treatments and must be stated in the name (§5.4.2.2 a). Do not assume it is unenhanced.

Evidence

  • GB/T · Table A.1, row 钻石 (Diamond)

What this means for you

Before buying, check the recommended listing name "Diamond" 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

Care

care (cleaning)2 sources compared

Diamond — care (cleaning): ultrasonic and steamer: relatively safe; note: take care if the stone has feathers or is included.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (cleaning): Lint-free cloths, commercial jewellery cleaners and household detergents are safe; powdered abrasive cleansers, ultrasonic and steam cleaners are not for home use, as the last two can loosen stones, which is why professionals check settings first.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (heat): Almost no acid harms it; the real threat is sudden, extreme temperature change, which can start or spread cracks; it burns at about 850 °C, a temperature house fires and jewellers' torches can reach.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (wear): It can scratch any precious metal used in settings, so a diamond that has worked loose in its setting can wear through a prong over time.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (wear): It has cleavage directions, so a hard blow can still split it, whether during setting or in wear; shapes with points are often set with prongs guarding the corners.

GIA Gem Encyclopedia (care guide)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (special care): coloured diamonds heated to alter colour: normal care.

AGTA Gemstone Information Manual, 17th ed.

Treatment state
treated
Only after these treatments
heating
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (special care): laser-drilled to improve appearance (colourless to faint yellow and coloured stones alike): normal care.

AGTA Gemstone Information Manual, 17th ed.

Treatment state
treated
Only after these treatments
laser drilling
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (special care): coated to hide an off-colour (colourless to faint yellow): care depends on the method, as recutting, steaming, ultrasonic and sometimes alcohol can spoil colour and look; coated to a fancy colour: special care (SC), as recutting, steaming and ultrasonic can do the same.

AGTA Gemstone Information Manual, 17th ed.

Treatment state
treated
Only after these treatments
coating
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (special care): hardened filler in surface cavities or fractures: special care (SC); recutting or extreme heat can remove the filler.

AGTA Gemstone Information Manual, 17th ed.

Treatment state
treated
Only after these treatments
filling
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (special care): HPHT-treated for colour or clarity: normal care for colourless to faint yellow stones (the care column is blank on the coloured-diamond row).

AGTA Gemstone Information Manual, 17th ed.

Treatment state
treated
Only after these treatments
high pressure high temperature treatment
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (special care): irradiated and/or heated to fancy colours: normal care except green; do not heat treated green stones, as the colour may change; some green stones were radium-irradiated and must be handled according to safety requirements.

AGTA Gemstone Information Manual, 17th ed.

Treatment state
treated
Only after these treatments
irradiation
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (setting): prong, bezel, flush, channel and pavé: relatively safe; note: four perfect cleavages; heavily included stones, or those with feathers or fractures near the girdle, need extra care.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

care (repair)2 sources compared

Diamond — care (repair): all irradiated coloured diamonds: avoid heat, which alters the colour.

Gems & Gemology 1987 (Martin)

Treatment state
treated
Only after these treatments
irradiation
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (repair): colourless diamond: Jeweller's torch, pickle pot and polishing: relatively safe; thermal shock: use caution; note: included stones need extra care. Coloured diamond: pickle pot and polishing: relatively safe; thermal shock: use caution; jeweller's torch: avoid; note: natural greens should not be heated, as heat alters the colour; included stones need extra care.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (repair): During repair a bench jeweller can use methods that shield the diamond from the torch's hot flame.

GIA Gem Encyclopedia (care guide)

Treatment state
any treatment state
Applies only to
fancy-colour diamonds
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — care (display): heat in the display case, sunlight and artificial light: relatively safe.

Gems & Gemology 1987 (Martin)

Treatment state
untreated
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.

Common care questions and matching entries

Each question links to the matching entries on this page; whether they answer it fully, go by the entry wording.

This table scrolls sideways on narrow screens.

QuestionMatching entries
Can it go in an ultrasonic or steam cleaner?ultrasonic and steamer: relatively safe; note: take care if the stone has feathers or is included; Lint-free cloths, commercial jewellery cleaners and household detergents are safe; powdered abrasive cleansers, ultrasonic and steam cleaners are not for home use, as the last two can loosen stones, which is why professionals check settings first
Heat and thermal shockAlmost no acid harms it; the real threat is sudden, extreme temperature change, which can start or spread cracks; it burns at about 850 °C, a temperature house fires and jewellers' torches can reach; all irradiated coloured diamonds: avoid heat, which alters the colour; colourless diamond: Jeweller's torch, pickle pot and polishing: relatively safe; thermal shock: use caution; note: included stones need extra care. Coloured diamond: pickle pot and polishing: relatively safe; thermal shock: use caution; jeweller's torch: avoid; note: natural greens should not be heated, as heat alters the colour; included stones need extra care; fancy-colour diamonds: During repair a bench jeweller can use methods that shield the diamond from the torch's hot flame
Light and displayheat in the display case, sunlight and artificial light: relatively safe
Wearing limits (knocks, settings)It can scratch any precious metal used in settings, so a diamond that has worked loose in its setting can wear through a prong over time; It has cleavage directions, so a hard blow can still split it, whether during setting or in wear; shapes with points are often set with prongs guarding the corners; prong, bezel, flush, channel and pavé: relatively safe; note: four perfect cleavages; heavily included stones, or those with feathers or fractures near the girdle, need extra care

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.

untreated

any treatment state

treated (Only after these treatments: heating)

treated (Only after these treatments: laser drilling)

treated (Only after these treatments: coating)

treated (Only after these treatments: filling)

treated (Only after these treatments: high pressure high temperature treatment)

treated (Only after these treatments: irradiation)

Durability and wearing

Toughness

Tough in tightly bonded directions; can be cleaved along cleavage directions by a hard blow

Sources GIA Gem Encyclopedia (care guide)

Treatments and identification leads

Values not givenThe treatments registered for Diamond are coating, filling, HPHT treatment and laser drilling, all with status treated; stability and market prevalence are all "—", meaning the cited source gives no value, not "none". Identification cluesAs identification leads: coated stones show weaker lustre under a loupe, lacking adamantine lustre, and the film may be seen peeling locally. Filled fractures show a flash effect, appearing orange-yellow or violet to purplish red, pink and similar colours in darkfield illumination, and blue to bluish green, greenish yellow, yellow and similar colours in brightfield illumination. HPHT treatment may show feathers around inclusions, sometimes containing black graphite; diamonds treated at high temperature and low pressure may show graphitized fractures; and under both long-wave and short-wave UV, HPHT-treated type Ia diamonds that are yellow or yellowish green fluoresce a strong chalky yellowish green or greenish yellow. Laser drilling may show white tubular channels inside that leave nearly round openings where they reach the surface, or centipede-like inclusions extending to the surface, sometimes with residual black material not fully removed.

This table scrolls sideways on narrow screens.

TreatmentMarket frequency (CIBJO)Stability (CIBJO)GB/T 16552 categoryJJA/AGL listingIdentification leads
coatingStatus: treated——Treatmentcoating (any colour)See identification leads
fillingStatus: treated——Treatment—See identification leads
high pressure high temperature treatmentStatus: treated——Treatmenthigh pressure high temperature (HPHT) (any colour)See identification leads
laser drillingStatus: treated——Treatmentlaser drilling (any colour)See identification leads
Irradiation (often followed by heating)——Treatment——
irradiation———irradiation (any colour); irradiation (black)—
impregnation with a colourless agent———impregnation with a colourless agent (any colour)—
internal laser drilling———internal laser drilling (any colour)—
carbonisation (heating)———carbonisation (heating) (black)—

Where each treatment acts (schematics): Coated · Filled / Fracture-filled · HPHT treated · Laser-drilled

“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16553—2017; GB/T 16552—2017 Table B.1; 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 2 names for Diamond in non-Latin scripts: 1 with no restriction recorded on use as a name, 1 that must not be used as a name.

Standard and listing namesThe Chinese formal name for Diamond is given in GB/T 16552—2017 Table A.1, and the suggested listing name is Diamond. Trade and mineralogical namesThe mineralogical name is Diamond (carbon), and the trade name or synonym is the Chinese mineralogical term for diamond, registered as a synonym with no restriction on use. The Chinese name meaning “South African diamond” is a market name but is not an acceptable name: under GB/T 16552—2017, origin should not form part of the name, and it is not a trade name. Names in four languagesThe four-language names are given in Simplified Chinese, Traditional Chinese, English (Diamond) and Japanese (a transliteration and a kanji name, the GSJ (Japan) formal name). Institution usageAmong authority wordings, the FTC lists Diamond and CIBJO (Gemmological Laboratories Book 2024) lists Diamond; GIA and Gem-A have not been checked, and bodies without a recorded wording show the entry's own English name, which does not represent their position. National standard namesNational and regional formal names: Germany (RAL) Diamant; the EU Diamond; India (BIS) Diamond / Heera (हीरा); France (DGCCRF) Diamant, with synthetic diamond required to be labelled “diamant de synthèse” or “diamant de laboratoire”; Australia (GAA) Diamond, where the geographical indication for Argyle pink diamonds is protected.

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.

NameTypeMatchingUse as a nameBasis
no restriction recorded (1)
金刚石Simplified Chinesesynonymmatched automaticallyno restriction recordededitorial ruling (no clause cited)
not to be used as a name (1)
南非钻石Simplified Chinesemarket namematched automaticallynot to be used as a nameGB/T 16552—2017 5.1.2.1 b); Note: GB/T 16552—2017 §5.1.2.1 b) uses it as the example of a rule: origin must not form part of the name (a counter-example, not a trade name).

How each authority words this name: see Names › Authority wording.

Authority wording

GIA, FTC, CIBJO, Gem-A
Diamond (on record for FTC, CIBJO (16 CFR Part 23 §23.12; CIBJO Gemmological Laboratories Book 2024); GIA, Gem-A unchecked — bodies without a recorded wording show the entry's own English name)
GSJ (Japan) formal name
ダイヤモンド／金剛石
Chinese formal name
钻石 (GB/T 16552—2017 Table A.1)
Mineralogical name
Diamond (carbon)

Four-language names

简体中文
钻石
繁體中文
鑽石
English
Diamond
日本語
ダイヤモンド／金剛石

National and regional formal names

Germany (RAL)
Diamant
European Union
Diamond
India (BIS)
Diamond / Heera (हीरा); BIS hallmarking mandatory for diamonds ≥ 0.25 ct
France (DGCCRF)
Diamant; DGCCRF: "diamant de synthèse" ou "diamant de laboratoire" obligatoire
Australia (GAA)
Diamond; Argyle pink diamond geographic designation protected

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 species
Mineral chemical class
Native elements
Construction or treatment status
Natural identity; treatment status unknown

Treatments listed by standards

GB/T Table B.1In the Diamond row of GB/T 16552—2017 Annex B, Table B.1, laser drilling, coating, filling, irradiation (often followed by heating) and HPHT treatment are all listed as treatment, with the effects respectively of improving clarity, changing colour and other aspects of appearance, improving or changing durability and appearance, changing colour, and improving or changing colour. JJA/AGL designationsIn the JJA/AGL (Japan) 2025 table, Diamond is listed under the species diamond in any colour, with an untreated tier listed as well; high pressure high temperature (HPHT) is recorded as HPHT treated, coating as coated, irradiation as irradiated, impregnation with a colourless agent as filled, and laser drilling and internal laser drilling as laser-drilled. Black Diamond is also listed under the species diamond, in black; the source lists no untreated tier, carbonisation (heating) is recorded as heated, and irradiation as irradiated.

GB/T 16552-2017, Annex B, Table B.1

Table B.1, row “Diamond” (p.14):

This table scrolls sideways on narrow screens.

MethodEffectCategory
Laser drillingImproves clarityTreatment
CoatingChanges colour and other aspects of appearanceTreatment
FillingImproves or changes durability and appearanceTreatment
Irradiation (often followed by heating)Changes colourTreatment
HPHT treatmentImproves or changes colourTreatment

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 nameSpeciesColourListed in the tableNotes
DiamondDiamondany colouran untreated tier is listed; high pressure high temperature (HPHT) (HPHT treated); coating (Coated); irradiation (Irradiated); impregnation with a colourless agent (Filled / Fracture-filled); laser drilling (Laser-drilled); internal laser drilling (Laser-drilled)
Black DiamondDiamondblackthe source lists no untreated tier; carbonisation (heating) (Heated / Heat-treated); irradiation (Irradiated)no dedicated entry on this site; shown on the broader entry

JJA/AGL definitions and nomenclature (2025 revision), table of principal gem names, p.14

How to read the JJA/AGL table: see the Gem treatments page.

What it is and how it's identified

Diamond is composed mainly of C and may contain trace elements such as N, B and H; type I contains N, type II contains very little N, and within type II, type IIa contains no B and type IIb contains B. The phase of Diamond is diamond; the structure is crystalline and cubic, with common crystal forms of octahedra, rhombic dodecahedra and cubes. Mohs hardness is 10, with medium cleavage; this site notes that hardness alone is not enough to judge durability. Density is 3.51–3.53 g/cm³; this site notes that the cited clause gives 3.52 with a tolerance of ±0.01, from which the limits are derived. The optic character is isotropic, with occasional anomalous extinction; refractive index 2.417, no birefringence, and dispersion 0.044; untreated Diamond has an adamantine lustre. On spectra, the intrinsic infrared peaks lie between 1500cm-1 and 2680cm-1, and diamonds are classified as types Ia, Ib, IIa and IIb according to the form in which nitrogen and boron are present and the corresponding infrared features; the characteristic Raman peak at 1332cm-1 reliably distinguishes opaque black Diamond from imitations such as black synthetic moissanite.

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”.

Definition

Diamond — nomenclature status: IMA status G: grandfathered (described before the IMA existed, and generally regarded as a valid species).

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Diamond — composition (chemistry): Carbon (C) is the main element; N, B and H may be present as trace elements. Nitrogen is present in Type Ⅰ, while Type Ⅱ holds only a very small amount of N. Boron is absent from Type Ⅱa and present in Type Ⅱb.

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-22
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-22)
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2026-09-22

Diamond — composition (phase): diamond

CIBJO Gemmological Laboratories Book 2024

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Source
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2026-09-22

Structure

Diamond — structure (overall): crystalline

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
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2026-09-21

Diamond — structure (crystal system): cubic

GB/T 16553—2017

Does this standard apply
applies to this entry
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Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
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2026-09-21

Diamond — structure (crystal habit): Common crystal forms are the octahedron, the rhombic dodecahedron and the cube; crystal faces commonly show step-like growth striations, growth cones or etch figures.

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-22
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-22)
Fact checked on
2026-09-22

Durability

Diamond — Mohs hardness: 10

GB/T 16553—2017

1234567891010References (diamond = value, bar = range; below)

Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, Orthoclase 6–6.5, Topaz 8 (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))

Mohs hardnessSource: GB/T 16553—2017
Does this standard apply
applies to this entry
General note
hardness only, not durability
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — cleavage: moderate

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
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2026-09-21

Physical properties

Diamond — density: 3.51–3.53 g/cm³

GB/T 16553—2017

0.51.52.53.54.55.56.57.53.51–3.53
Specific gravitySource: GB/T 16553—2017
Does this standard apply
applies to this entry
Qualification

The clause we cite gives 3.52, with a stated tolerance of ±0.01. The range shown here is worked out from that.

Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Optical

Optical effects on record: colour change

Diamond — optic character: isotropic; anomalous extinction appears occasionally

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — refractive index: 2.417

GB/T 16553—2017

1.31.51.71.92.12.32.52.72.93.13.32.417
Refractive indexSource: GB/T 16553—2017
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — birefringence: none

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — dispersion: 0.044

GB/T 16553—2017

00.050.10.150.20.250.30.044
DispersionSource: GB/T 16553—2017
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — transparency: transparent, translucent, opaque.

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
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2026-09-22

Diamond — pleochroism: none

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — fluorescence (overall): none to strong, blue, yellow, orange-yellow, pink; fluorescence under short wave is usually weaker than under long wave.

GB/T 16553—2017

UV fluorescenceblueyelloworange-yellowpinknone–strongDots are illustrative colours built from the colour names, not measured values

Treatment state
untreated
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — spectrum (UV-visible): type Ia diamond: in the vast majority 415 nm absorption peak.

GB/T 16553—2017

400450500550600650700 nmtype Ia diamond415
Absorption spectrum (schematic)Line = absorption peak; hatching = absorption band; heavier or darker = higher recorded strength grade (not a measured intensity); Schematic: positions and strength grades as given by the cited source, not a measured curveSource: GB/T 16553—2017
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — spectrum (infrared): Diamond's intrinsic peaks fall between 1 500 cm⁻¹ and 2 680 cm⁻¹; the characteristic infrared absorption bands produced by C-C bond vibration sit at 2 030 cm⁻¹, 2 160 cm⁻¹ and 2 350 cm⁻¹, which is what lets diamond be told apart from its imitations.

Four types — Ⅰa, Ⅰb, Ⅱa and Ⅱb — are set apart by how nitrogen and boron occur and by the matching infrared signature, and Type Ⅰa can be further split into ⅠaA, ⅠaAB and ⅠaB. Characteristic band positions run as follows: 1 282 cm⁻¹ for Type ⅠaA; 1 175 cm⁻¹ and others for Type ⅠaB; 1 130 cm⁻¹ and 1 344 cm⁻¹ for Type Ⅰb, which carries isolated nitrogen; 2 801 cm⁻¹ and others for Type Ⅱb, which carries boron.

Type Ⅱa carries no nitrogen, or only a very small amount of nitrogen polymer.

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-22
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-22)
Fact checked on
2026-09-22

Diamond — spectrum (Raman): Diamond's Raman characteristic peak sits at 1 332 cm⁻¹, and it can effectively separate opaque black diamond from its imitations (black synthetic moissanite, for example).

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-22
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-22)
Fact checked on
2026-09-22

Diamond — optical effect (colour change): seen; extremely rare

GB/T 16553—2017

Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — magnification: mineral inclusions, pale to dark in colour, cloud, pinpoint inclusions, feather, growth striations, extended natural, natural, cleavage, sharp facet edges.

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

body colour2 sources compared

Diamond — body colour: colourless to yellow or brown, pink (rarely red), green, blue, orange, grey, black.

CIBJO Gemmological Laboratories Book 2024

Treatment state
untreated
Qualification

In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Labradorite, Topaz, Zircon and other entries also name colourless.

General note
colour alone is not identity
Source & check 2026-09-22
Source
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2026-09-22

Diamond — body colour: colourless to light yellow (brown, grey) series: colourless, pale yellow, light yellow, light brown, light grey and similar colours. Coloured series: yellow, brown, grey, and light to dark blue, green, orange, pinkish red, red, purplish red, black and other colours.

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
Qualification

The colours GB/T 16553—2017 lists for Synthetic Diamond overlap with this entry: yellow, colourless, blue and purplish red.

General note
colour alone is not identity
Source & check 2026-09-26
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-26)
Fact checked on
2026-09-26

How the sources relate

CIBJO Gemmological Laboratories Book 2024 and GB/T 16553—2017

complementary, no conflict

The two entries largely agree: colourless to yellow or brown, plus pink, red, green, blue, orange, grey and black. The CIBJO Gemmological Laboratories Book notes that red is rare; GB/T 16553—2017 also lists purplish red and groups the colours into a colourless-to-light-yellow (brown, grey) series and a coloured series.

CIBJO definitions
colour change

Quality factors

Diamond — quality factor (lustre): adamantine

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Each row's “Source & check” expands to the full source; the date beside it is the fact check date.

2.42.52.62.72.833.544.55Refractive indexSpecific gravity12345Diamond

This material (RI / SG midpoints): 2.417 / 3.52; Closest values: 1Sphalerite 2.369 / 4, 2Synthetic Moissanite 2.67 / 3.22, 3Artificial Strontium Titanate 2.409 / 5.13, 4Rutile 2.753 / 4.23, 5Synthetic Rutile 2.76 / 4.26

Show the full chart (330 registered materials)1.41.51.61.71.81.922.12.22.32.41234567Refractive indexSpecific gravity13Diamond

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

Refractive index × specific gravity (all registered materials)Each dot is one material's registered refractive index and specific gravity (range midpoints, not measurements); gold = this material, dark = the nearest few (picked on this site by distance in RI ÷ 0.02 and SG ÷ 0.1, leaving out near-identical varieties of the same species)Source: each material's registered refractive index and specific gravity facts (GB/T 16553 and others; sources on each entry)

Testing and market

The tests the CIBJO laboratory protocol requires for this material, and what each method means, are in the protocol table on the laboratory testing page: §6.1.22, §6.1.23.

How far testing can go

Diamond that has undergone coating can be identified by the following features: Under magnification the coated surface has a weak luster that is not adamantine, the structure looks grainy, and the film can be seen peeling off in places.

GB/T 16553—2017

Treatment state
treated
Does this standard apply
can be followed as a reference only
Treatment
coating
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (coating) (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond that has undergone filling can be identified by the following features: Under magnification the filled fissures show a flash effect: in dark-field illumination the flash is orange-yellow, or purple to purple-red and pink; in bright-field illumination it is blue to blue-green, green-yellow or yellow.

The filler may contain residual bubbles, flow structures and fine fissures; the filled area looks white and hazy with reduced transparency, and areas of incomplete filling may occur. Compositional analysis (XRF and the like) can detect an abnormal content of foreign elements such as lead.

GB/T 16553—2017

Treatment state
treated
Does this standard apply
can be followed as a reference only
Treatment
filling
Source & check 2026-09-22
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (filling) (locator checked 2026-09-22)
Fact checked on
2026-09-22

Diamond that has undergone high pressure high temperature treatment can be identified by the following features: Under magnification, feather fissures appear around the inclusions, and black graphite is sometimes visible within them; where the stone has been treated at high temperature and low pressure, graphitization can be seen in the feather fissures.

Type Ⅰa HPHT-treated yellow or yellow-green diamond gives a strong chalky yellow-green or green-yellow fluorescence under both long-wave and short-wave ultraviolet light. In practice a conclusion is generally reached only by interpreting infrared, near-infrared, ultraviolet-visible and laser photoluminescence spectra together.

GB/T 16553—2017

Treatment state
treated
Does this standard apply
can be followed as a reference only
Treatment
high pressure high temperature treatment
Source & check 2026-09-22
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (high pressure high temperature treatment) (locator checked 2026-09-22)
Fact checked on
2026-09-22

Diamond that has undergone laser drilling can be identified by the following features: Under magnification a white tubular channel runs inside the diamond and leaves a nearly round opening at the surface; or a centipede-like inclusion reaches the surface along unnaturally curved fissures, sometimes with black residue that was not removed.

GB/T 16553—2017

Treatment state
treated
Does this standard apply
can be followed as a reference only
Treatment
laser drilling
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (laser drilling) (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — how far testing can go (instrumental testing): Thermal conductivity is high (0.35 cal per cm per second per degree); under X-rays most specimens fluoresce sky blue or pale blue and a very few do not fluoresce; under cathode rays they emit blue or green light; type IIa is an excellent insulator; type IIb is a high-quality high-temperature semiconductor.

GB/T 16553—2017

Treatment state
untreated
Does this standard apply
applies to this entry
Source & check 2026-09-21
Source
  • GB/T 16553—2017 Gems — Testing (GB/T): §5.1.1 (locator checked 2026-09-21)
Fact checked on
2026-09-21

Diamond — what the CIBJO laboratory protocol says to watch for: irradiation, HP-HT, coatings, clarity enhancement, synthetics for diamond grading, see ISO 24016.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
colourless diamond (identification only)
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — what the CIBJO laboratory protocol says to watch for: HP-HT, coatings, clarity enhancement, synthetics

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
coloured diamond
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — notes on test methods in the CIBJO laboratory protocol:

Applies only to: colourless diamond (identification only); CIBJO laboratory protocol, in its own order; only the notes registered on this site
Test methodWhat the protocol notes for it
DiamondView: Possibly synthetic

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
colourless diamond (identification only)
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Diamond — notes on test methods in the CIBJO laboratory protocol:

Applies only to: coloured diamond; CIBJO laboratory protocol, in its own order; only the notes registered on this site
Test methodWhat the protocol notes for it
UV-Visible(-NIR) spectroscopy: Low temperature;
Geiger counter: Green and black diamonds

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
coloured diamond
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

Diamond is listed in the CIBJO Gemmological Laboratories Book 2024 under the entry Diamond, defined as the mineral species diamond, IMA status G, 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. A further entry is based on the IMA Mineral List, under the entry Diamond, recorded as Diamond C G ?, and cross-checked against the RRUFF/IMA master mineral list, on the basis of public domain data.

This table scrolls sideways on narrow screens.

TermClauseDefinitionCross-check
Diamond7.2.1.72colourless to yellow or brown, pink (rarely red), green, blue, orange, grey, black; transparent, translucent, opaqueDefined directly by CIBJO; also present in the GB/T annex.
DiamondIMA Mineral List entryDiamond C G ?Cross-checked against the RRUFF/IMA master mineral list (public domain data).

Evidence and sources

Authority basis and clause sources

GB/T 16552—2017
Listed Table A.1 “Diamond” · Source
IMA Mineral List 2026-07
Listed “Diamond” · Source
CIBJO Gemmological Laboratories Book 2024
Listed §7.2.1.72 “Diamond” · Source

Sources

Further reading

Related pages

Treatments recorded for this material

Recorded cultural contexts

Birthstone list

The U.S. Jewelers of America roster lists Diamond for April; the U.K. National Association of Jewellers chart lists Diamond as traditional for April; and Japan's JJA 2021 revised roster lists Diamond for April. This records trade-association convention only; it does not establish material identity, natural origin, treatment, provenance, or effect.

Relation
Industry list inclusion

This table scrolls sideways on narrow screens.

Publisher or holderRegionFrom / periodSource and locator
Jewelers of AmericaUnited States1912 to the presentJewelers of America, “Birthstone Jewelry” (web page, consulted 2026-08-22)
Birthstone roster table, April row: Diamond
Japan Jewellery AssociationJapanfrom 20 December 2021Tanjoseki (Japanese birthstone roster, Japan Jewellery Association page; revision of 20 December 2021)
2021 revised birthstone roster, April row: Diamond
National Association of JewellersUnited Kingdom—National Association of Jewellers, “Zodiac Birthstones Jewellery: Star Signs, Gemstones and Their Meaning” (web page, consulted 2026-08-22)
Zodiac birthstone chart, April row: Diamond (Traditional)

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 (Diamond) is marked.

This table scrolls sideways on narrow screens.

PageContentStatus
Browsing familyNative-element mineralsLive
Treatments recorded for this materialFilled / Fracture-filled, Irradiated, Coated, HPHT treated, Laser-drilled, Heated / Heat-treatedLive
Related articlesTo be added (placeholder)Planned

Who maintains this page

The material facts in the Diamond 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.

Facts editor
Ralph
Reviewer
June
How facts are checked
Each fact is matched to the clause it cites; facts checked between 2026-09-21 and 2026-09-26
Last revised
2026-10-12
Purpose
Lets buyers and sellers check naming, disclosure and material facts clause by clause.

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