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UnderstandWhat it is, what people ask, how far this page goes
Natural organic and biogenic materials · Organic or biogenic material · Cultured formation; treatments recorded separately
Cultured Pearl
Also known asCultivated pearl
A pearl formed inside a mollusc with human intervention; GB/T 16552-2017 clause 5.1.2.3 allows it to be called simply "pearl". 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 Cultured Pearl forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify Cultured PearlIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of Cultured Pearl3 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing Cultured PearlCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness and refractive index of Cultured PearlEach value with its source and check date
- Cultured Pearl in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name, names in national standards; and: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Listing and disclosing Cultured PearlThe 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
Cultured pearls are pearls grown with human intervention and care. In the typical path, a technician harvests mantle tissue from a sacrificed donor of the same species and places a shell bead, plus a small piece of mantle tissue, inside a host mollusk's gonad — or several pieces of mantle tissue without a bead into the host's mantle. Where a bead is used, the mantle tissue grows into a sac around it and secretes nacre inward onto the bead, eventually producing a cultured pearl; where no bead is used, nacre forms around each implanted tissue piece. The pearl sac arises when grafted epithelium cells multiply and join, a biomineralization process.
Scope: Covers the human-induced origin of both bead-nucleated (beaded) and tissue-nucleated (non-beaded) cultured pearls; distinguished from the spontaneous origin of natural pearls, and does not address man-made products such as imitation pearls.
Sources GIA Pearl Description · GIA Pearl Description (Chinese edition) · G&G Fall 2021 +1
Where it forms
Gonad or mantle of the host mollusk: the environment where grafted tissue and any bead form a pearl sac and deposit nacre.
Sources G&G Fall 2021 · GIA Pearl Description
Culturing farms (marine or freshwater); today most mollusks used are raised specifically for the purpose.
Sources G&G Fall 2021 · GIA Pearl Description
How it forms, step by step
Mantle tissue is taken from a donor mollusk and cut into small pieces (saibo).
The piece of mantle tissue is implanted with a shell bead into the host's gonad, or several pieces without a bead are implanted into the host's mantle.
Sources GIA Pearl Description (Chinese edition) · G&G Spring 2013
The grafted epithelium cells multiply and join, creating a pearl sac around the bead nucleus (when one is present).
The pearl sac secretes nacre inward, depositing layer upon layer onto the bead or around the implanted tissue to form the cultured pearl.
Link to appearance
The nacre secreted by the pearl sac controls the luster, color and nacre thickness of a cultured pearl; the donor tissue (saibo) strongly influences color and nacre thickness, so appearance varies with donor and host species.
Sources G&G Spring 2013 · G&G Fall 2021
Timescale
Sources give no universal growth time for cultured pearls; beaded saltwater cultured pearls such as P. maxima generally require a minimum two-year growth period for the thickest nacre, but times vary with species and farm.
Sources G&G Fall 2021
Related base materials
- Mollusk (host): biogenic-host | Cultured pearls form inside a host mollusc when a pearl sac, induced by implanted tissue/a nucleus, secretes nacre
- Shell bead nucleus (freshwater mussel shell): inserted-nucleus | Beaded cultured pearls use a bead ground from freshwater mussel shell as the nucleus, around which nacre is gradually deposited
Supporting findings
Cultured pearl growth requires human intervention and care: a technician inserts mantle tissue with a shell bead (or tissue pieces alone) into a host mollusk's gonad or mantle.
Evidence grade AScope: Authoritative description covering both bead-nucleation and tissue-only paths.
Sources GIA Pearl Description · GIA Pearl Description (Chinese edition)
The grafted mantle epithelium cells multiply and join, creating a pearl sac around the bead nucleus, which then lays down nacre inward to produce a cultured pearl.
Evidence grade AScope: Describes pearl sac formation and deposition for bead-cultured pearls, based on Pinctada maxima research.
Beaded saltwater cultured pearls are generally grown after a piece of mantle tissue (saibo) has been transplanted, and the graft is the main factor controlling the cultured pearl's colour and nacre thickness.
Evidence grade AScope: For beaded saltwater cultured pearls; from xenotransplantation experiments on the role of Pinctada donor tissue.
Recorded localities
This is an organic material; its localities are the harvest or culture areas (waters or species ranges) recorded by authoritative sources.
Asia
- ChinaFreshwater and saltwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- Taiwan, ChinaFreshwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- VietnamFreshwater and saltwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- Lake Biwa, Shiga, JapanFreshwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- Lake Kasumigaura, Ibaraki, JapanFreshwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- ThailandFreshwater and saltwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- IndiaFreshwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- PhilippinesFreshwater and saltwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- Korea (as printed)Freshwater
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- JapanSaltwater; akoya
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- IndonesiaSaltwater; akoya and South Sea
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- MyanmarSaltwater; Pinctada maxima since 1957
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
North America
- United StatesFreshwater; cultured blister pearls
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- Guaymas, Sonora, MexicoSaltwater; rainbow-lipped oyster since 2000
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
Oceania
- AustraliaSaltwater; South Sea (Pinctada maxima)
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- French PolynesiaSaltwater; major producer of Pinctada margaritifera (Tahiti cultured pearl)
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
- Cook IslandsSaltwater; Pinctada margaritifera
Sources CIBJO Pearl Book 2024
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1)
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.
How it is identified
Cultured and natural pearls may look almost identical in colour and lustre, so appearance cannot serve as the deciding evidence. A laboratory must combine routine tests with UV-Vis reflectance spectroscopy, X-ray fluorescence and real-time X-radiography, and gauge nacre thickness, to judge whether a bead or tissue nucleation was used; the call belongs to an accredited institute.
Evidence grade AScope: Judging a cultured pearl is laboratory work whose conclusion must come from an accredited body; the reader should not decide from appearance alone.
Sources GIA: How GIA Identifies Pearls
Other research findings
For shell bead nuclei, the usual raw material is American freshwater mussels of the family Unionidae, which are the source most widely used for bead-cultured saltwater pearl production.
Evidence grade AScope: Describes the traditional nucleus material; alternatives such as plastic and resin were experimental and not widely adopted.
In pearl identification, nacre thickness in bead-cultured pearls is measured by real-time microradiography, whenever the nacre looks thin or at the client's request.
Evidence grade AScope: A laboratory method; nacre thickness is a measurable indicator used in origin assessment.
Sources GIA: How GIA Identifies Pearls
CIBJO's definition of cultured pearls covers pearls produced, with human intervention, inside productive living molluscs within a cultured pearl sac.
Evidence grade AScope: The naming definition (clause 5.55), also general clause 3.2; defines cultured pearls by human intervention and the cultured pearl sac.
Sources CIBJO Pearl Book 2024
Cultured pearls are assessed by lustre, nacre thickness, surface, shape, colour and matching; GIA's seven Pearl Value Factors are Size, Shape, Color, Nacre, Luster, Surface and Matching. For bead-nucleated (bead-cultured) pearls, nacre thickness is a measurable factor tied to the culturing period and affecting colour, lustre and durability, but thickness does not equal nacre quality. Saltwater and freshwater cultured pearls differ in emphasis: bead-cultured saltwater pearls focus more on nacre thickness, whereas freshwater cultured pearls are mostly tissue-nucleated and so the nacre-thickness measure usually does not apply, with emphasis on lustre, surface and shape. Imitation pearls are not subject to pearl quality assessment.
Evidence grade AScope: 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. Pearl quality assessment must be issued by an accredited laboratory for a specific specimen.
Sources CIBJO Pearl Book 2024 · GIA: How GIA Identifies Pearls
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Sources describe culturing paths and the pearl sac mechanism but give no universal growth time; actual time varies by species and farm.
- This record does not subdivide marine/freshwater or specific categories (covered by other records).
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
- Cultured Pearl (state freshwater or saltwater and any treatments)
GB/T 16552—2017 Table A.3 “Cultured Pearl(Pearl)”, 5.1.2.3 b) · CIBJO Gemmological Laboratories Book 2024 §7.2.2.9 “Pearl”
Construction or treatment status
Cultured formation; treatments recorded separately
Treatments recorded for this material: Bleached, Dyed, Irradiated
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
"Cultured Pearl" is a market name rather than a mineral species name; before using it, verify: Laboratory identification required before the name is used.
What this means for you
Before buying, check the recommended listing name "Cultured Pearl (state freshwater or saltwater and any treatments)" 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
- 2026-09-01
Trade-name ruling
- Laboratory identification required before the name is used.
- Suggested listing name
- Cultured Pearl (state freshwater or saltwater and any treatments)
Care and wear
The normal and special care that applies to all natural and cultured pearls, and so to Cultured Pearl (CIBJO Pearl Book §7.1, §7.2; the source says this advice counts as normal across the whole range and should be passed on to the buyer), is set out in full under care on the Pearl entry.
Care
Cultured Pearl — care (special care): bleached, dyed (including coloured nuclei or heat-assisted chemical treatment to grey or black) or irradiated to blue, grey, black or bronze: special care (SC); keep away from cosmetics.
AGTA Gemstone Information Manual, 17th ed.
- Treatment state
- treated
- Only after these treatments
- bleaching, dyeing, irradiation
Source & check 2026-09-26
- Source
- AGTA Gemstone Information Manual, 17th edition (August 2026) (AGTA): p.XII–XIII, Gemstone Information Chart, Pearl Cultured B / D / R, CARE REQUIRED / SPECIAL ADVICE (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Durability and wearing
Toughness
Usually good toughness, but aging, dehydration and excessive bleaching can make some pearls more fragile
Sources GIA Gem Encyclopedia (care guide)
Treatments and identification leads
Registered treatmentsThe registered treatments for Cultured Pearl are dyeing, bleaching and irradiation. Values not givenDyeing and bleaching both have the status colour-treated, and irradiation the status irradiated or dyed; the stability and prevalence of all three are recorded as “—” (the cited source gives no value, not “none”). For dyeing, colour spots are visible under magnification, with the colour concentrated mostly at growth defects; under long-wave and short-wave UV the dye may give distinctive fluorescence; spectroscopically, dyed pearls differ from coloured freshwater pearls in Raman spectra and from coloured saltwater pearls in UV-visible and laser photoluminescence spectra. Bleaching can improve colour and appearance and is hard to detect. Irradiation can turn pearls black, greenish black, bluish black, grey and so on; under magnification, halo spots formed by irradiation are visible on the nacre layer, and the Raman spectrum usually has a very strong fluorescent background.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| dyeingStatus: colour treated | — | — | Treatment | — | See identification leads |
| bleachingStatus: colour treated | — | — | Optimization | — | See identification leads |
| irradiationStatus: irradiated or dyed | — | — | Treatment | — | See identification leads |
Where each treatment acts (schematics): Dyed · Bleached · Irradiated
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16553—2017; GB/T 16552—2017 Table B.1
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
How lab reports word it
Report wording for Cultured Pearl is set out under report wording on the Pearl entry.
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Cultured Pearl, the name register records "Cultivated pearl", for which no restriction on use as a name is recorded.
Standard and listing namesThe Chinese formal name of Cultured Pearl comes from the “Cultured pearl (pearl)” entry in GB/T 16552—2017 Table A.3; the suggested listing name is Cultured Pearl (state freshwater or saltwater, and any treatment), and the trade name or synonym is Cultivated pearl. Names in four languagesThe names are given in Simplified Chinese, Traditional Chinese, English (Cultured Pearl) and Japanese; for the GSJ (Japan) formal name, this site has not yet verified GSJ's wording for this name, and the entry's own Japanese names are shown. Institution usageFor authority wording, FTC records Cultured Pearl (16 CFR Part 23); GIA, CIBJO and Gem-A are unchecked, and bodies not checked show the entry's own English name, which does not represent their position. National standard namesGermany (RAL) uses Zuchtperle, noting “kultiviert”; the European Union uses Cultured Pearl; France (DGCCRF) uses Perle de culture, noting that “perle” without a qualifier means a natural pearl. Trade and mineralogical namesThe mineralogical name is described as a pearl formed inside a mollusc with human intervention.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| Cultivated pearlEnglish | synonym | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 養殖真珠／養殖パール (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 养殖珍珠 (GB/T 16552—2017 Table A.3, row “Cultured Pearl(Pearl)”)
- Mineralogical name
- Pearl formed in a mollusc with human intervention
- Trade names and synonyms
- Cultivated pearl (synonym)
Four-language names
- 简体中文
- 养殖珍珠
- 繁體中文
- 養殖珍珠
- English
- Cultured Pearl
- 日本語
- 養殖真珠／養殖パール
National and regional formal names
- Germany (RAL)
- Zuchtperle (RAL: "kultiviert")
- European Union
- Cultured Pearl
- France (DGCCRF)
- Perle de culture (DGCCRF: "perle" sans qualificatif = naturelle)
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural organic and biogenic materials
- Browsing family
- Pearl and molluscan shell materials
- Identity tier
- Organic or biogenic material
- Mineral chemical class
- Not applicable
- Construction or treatment status
- Cultured formation; treatments recorded separately
Treatments listed by standards
For Cultured Pearl, the Cultured Pearl (Pearl) row of GB/T 16552—2017, Annex B, Table B.1 lists the following: bleaching, which improves colour and other aspects of appearance, classed as optimization; dyeing, which improves or changes colour, classed as treatment; and irradiation, which changes colour, classed as treatment. In other words, bleaching counts as optimization, while dyeing and irradiation count as treatment. What Table B.1 is and how each grade is defined are explained on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Table B.1, row “Cultured Pearl (Pearl)” (p.17):
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| Method | Effect | Category |
|---|---|---|
| Bleaching | Improves colour and other aspects of appearance | Optimization |
| Dyeing | Improves or changes colour | Treatment |
| Irradiation | Changes colour | Treatment |
What Table B.1 is, and how the “see 5.4.1” grades are defined: see the GB/T 16552: optimization vs treatment page.
What it is and how it's identified
The composition of Cultured Pearl is mainly calcium carbonate (mainly aragonite, with calcite and a small amount of vaterite) and organic matter (mainly conchiolin), with water and various trace elements. Under GB/T 18781—2023, the nacre structure must be concentric layers or concentric radiating layers with pearly lustre; GB/T 18781—2023 does not apply to pearls that have been irradiated, dyed or otherwise treated. The CIBJO Blue Book separately recognises non-nacreous cultured pearls, in which the calcium carbonate has a crossed-lamellar structure and the surface often shows a flame structure and porcelaneous lustre, a typical example being cultured conch pearls. Mohs hardness under GB/T 16553—2017 is 2.5–4; cleavage usually not visible in aggregates; optical character aggregate; refractive index 1.53–1.68, noted as a spot-method reading and a common value rather than an absolute limit, with the clause having finer sub-ranges and the overall value used; birefringence not measurable on an aggregate. Coloured saltwater pearls show characteristic absorption peaks in the UV-visible spectrum; there are characteristic infrared absorption bands in the mid-infrared region caused by carbonate-ion vibrations in aragonite.
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
Cultured Pearl2 sources compared
Cultured Pearl: formed inside a mollusk, such as a shellfish or mussel, when human intervention prompts it to secrete nacre that then hardens.
GB/T 18781—2023
- Does this standard apply
- applies to this entry
- Qualification
GB/T 18781-2023 §3.2 note 1 requires the nacreous layer of a cultured pearl to show a concentric or concentric-radial structure with pearly lustre; the standard does not cover irradiated or dyed pearls.
Source & check 2026-09-17
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.2 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-17
Cultured Pearl: formed with human intervention in a cultured pearl sac; a separate non-nacreous class is recognised.
CIBJO Pearl Book 2024
- Qualification
Non-nacreous cultured pearls consist of calcium carbonate in a crossed-lamellar microarchitecture, usually with a flame-like surface pattern and a porcelaneous sheen; the cultured conch pearl is the standard example.
Source & check 2026-09-20
- Source
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.55, p.28; §5.140, p.38 (locator checked 2026-09-24)
- Fact checked on
- 2026-09-20
How the sources relate
- GB/T 18781—2023 and CIBJO Pearl Book 2024
The two authorities differ on whether a cultured pearl must consist of nacre. The Chinese national standard requires it to be nacre secreted by a mollusc under human intervention, with a concentric-layered nacreous structure and pearly lustre.
The CIBJO Blue Book recognises a separate class of non-nacreous cultured pearls, whose calcium carbonate is arranged in a crossed-lamellar microarchitecture, typically showing a flame-like surface pattern and a porcelaneous sheen — the cultured conch pearl being the standard example.
The same cultured conch pearl therefore qualifies as a cultured pearl under one framework and not under the other.
Cultured Pearl — composition (chemistry): mainly calcium carbonate (chiefly aragonite) and organic matter (chiefly conchiolin). Water and various trace elements are also present, in smaller amounts.
GB/T 18781—2023
- Does this standard apply
- applies to this entry
Source & check 2026-09-17
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.2 Note 1 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-17
Cultured Pearl — composition (inorganic components and trace elements): inorganic components: CaCO3, mainly aragonite, with calcite and a little vaterite. Seawater pearls contain relatively more Sr, S, Na and Mg and relatively little Mn; freshwater pearls are relatively rich in Mn and relatively poor in Sr, S, Na and Mg.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- GB/T 18781—2023 and GB/T 16553—2017
The two entries complement each other. GB/T 18781-2023 summarises a cultured pearl as calcium carbonate and organic matter, with water and various trace elements. GB/T 16553-2017 goes further: it names the minerals of the inorganic part (mainly aragonite, with calcite and a little vaterite) and describes how seawater and freshwater pearls differ in trace elements.
Structure
Cultured Pearl — structure (overall): The nacre has a concentric layered structure, or a concentric layered-radial one, and shows a pearly luster.
GB/T 18781—2023
- Does this standard apply
- applies to this entry
Source & check 2026-09-17
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.2 Note 1, §3.5 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-17
Cultured Pearl — structure (crystalline state): inorganic part: aragonite (orthorhombic) and calcite (trigonal) in radiating aggregates; organic part: amorphous.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- GB/T 18781—2023 and GB/T 16553—2017
The two entries complement each other. GB/T 18781-2023 describes the structure of the nacre (concentric layers, or concentric layers with a radial arrangement). The crystalline-state field of GB/T 16553-2017 gives the crystal systems of the minerals involved (aragonite is orthorhombic, calcite is trigonal, forming radial aggregates) and states that the organic part is amorphous. They do not conflict.
Durability
Mohs hardness2 sources compared
Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, Orthoclase 6–6.5, Topaz 8, Diamond 10 (Source: GB/T 16553—2017); Gypsum 1.5–2, Calcite 3, Quartz 7 (Source: Handbook of Mineralogy); Corundum 9 (Source: GIA Gem Encyclopedia (care guide))
Cultured Pearl — Mohs hardness: 2.5–4
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cultured Pearl — Mohs hardness: 2.5–3
GIA Gem Encyclopedia
- Qualification
The clause we cite covers the whole species. This entry is only one variety of it.
Source & check 2026-09-20
- Source
- GIA Gem Encyclopedia — Pearl (Gemological Institute of America): Section “Facts”, “Mohs Hardness” (locator checked 2026-09-28)
- Fact checked on
- 2026-09-20
Cultured Pearl — cleavage: generally not seen on an aggregate
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
stability2 sources compared
Cultured Pearl — stability: effervesces in acid
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cultured Pearl — stability: In addition to normal care, natural and cultured pearls shall have special care requirements that include instructions that they should not be worn while carrying out heavy work, should be kept away from all solvents and acids and not be subjected to high temperatures as well as ultrasonic cleaning.
CIBJO Pearl Book 2024
- Treatment state
- untreated
Source & check 2026-09-21
- Source
- CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7 Annex B, 7.2, p.49 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Physical properties
Cultured Pearl — feel (texture): feels gritty when two surfaces are rubbed together
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Cultured Pearl — optic character: aggregate
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — refractive index: 1.53–1.68
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives this as a value read by the spot (distant-vision) method. It is a common value, not an absolute limit.
- General note
- the clause has finer ranges
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — birefringence: not measurable on an aggregate
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — pleochroism: not measurable on an aggregate
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — fluorescence (overall): none to strong, light blue, yellow, green, pink-red.
GB/T 16553—2017
UV fluorescencelight blueyellowgreenpink-rednone–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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — spectrum (UV-visible): coloured seawater pearl: characteristic absorption peak.
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — spectrum (infrared): Carbonate-ion vibration in aragonite produces the diagnostic mid-IR bands
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): §5.3.2 (locator checked 2026-09-22)
- Fact checked on
- 2026-09-22
Cultured Pearl — optical effect (iridescence): rainbow colors that can shift, on or just below the pearl surface. A pearl may show iridescence. When it does, the grade is strong, obvious or ordinary.
GB/T 18781—2023
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.1: non-reflective grey or white background, away from brightly coloured objects, light source of colour temperature 5500 K–7200 K and colour rendering index above 90, pearl rolled and observed with the unaided eye
- Qualification
GB/T 18781-2023 §4.1.3 only grades iridescence in three bands and does not fold it into the colour grade. §4.1.4 states that iridescence is a supplementary description. It is not an identity or naturalness determination.
Source & check 2026-09-17
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.10, §4.1.3, §6.1 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-17
Cultured Pearl — magnification: concentric layers with a radial arrangement, growth striations on the surface, in bead-nucleated cultured pearls the nucleus may show parallel layering, surface growth striations on one side of a pearl grown attached to the shell, a layered structure on the opposite side.
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): §5.3.2 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl — body colour: colorless to yellow, pink red, green, blue, and purple.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
In chapter 5 of GB/T 16553—2017, the colour entries of Scapolite, Apatite, Apophyllite and other variety clauses also name colourless.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Quality factors
quality factor (lustre)2 sources compared
Cultured Pearl — quality factor (lustre): pearly
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cultured Pearl — quality factor (lustre): four grades by strength, evenness and image sharpness of the reflection: very strong (A) very bright, sharp and even, mirror-like with a very clear image; strong (B) bright, sharp and even with a clear image; medium (C) bright, with images of objects visible on the surface; weak (D) rather weak, objects reflected but blurred.
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.4: non-reflective grey or white background, away from brightly coloured objects, light source of colour temperature 5500 K–7200 K and colour rendering index above 90, sample compared against pearl reference samples
Source & check 2026-09-26
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.14, §4.4 Table 2, §6.4 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-26
Cultured Pearl — quality factor (surface): five grades by size, number, color and position of blemishes: excellent (A) smooth and fine to the eye, blemishes very hard to see; very good (B) very few pinpoint blemishes, hard to see; good (C) small blemishes, easy to see; medium (D) obvious blemishes covering under a quarter of the surface, none serious enough to affect use; ordinary (E) very obvious blemishes, serious ones covering over a quarter.
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.5: non-reflective grey or white background, away from brightly coloured objects, light source of colour temperature 5500 K–7200 K and colour rendering index above 90, sample cleaned and dried, then rolled and observed with the unaided eye
Source & check 2026-09-26
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.16, §4.5 Table 3, §6.5 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-26
Cultured Pearl — quality factor (nacre thickness): extra thick (A) ≥15%; very thick (B) 12%≤PT<15%; thick (C) 9%≤PT<12%; medium (D) 6%≤PT<9%; thin (E) <6%.
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.6: direct measurement (arbitration method), X-ray method or optical coherence tomography; PT = mean nacre thickness ÷ mean of the maximum and minimum diameter × 100
- Nucleation
- beaded
- Qualification
Table 4 excludes beaded cultured pearls from the Pinctada fucata martensii oyster: under normative Annex A they are graded in mm, as shown on the Akoya cultured pearl page. All non-beaded cultured pearls are graded A (extra thick) under §4.6.3.
Source & check 2026-09-26
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.17, §4.6.2 Table 4, §6.6 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-26
Cultured Pearl — quality factor (matching): three grades for multi-pearl jewelry by consistency: very good (A) uniform shape, luster and surface, harmonious color and size, graduated strand, centered straight clean drill holes; good (B) slight differences, fairly harmonious, roughly graduated, centered clean holes; ordinary (C) clear differences, holes slightly off-line with burrs.
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.7: determined against Table 5 after the sample has been cleaned and dried
- Qualification
For multi-pearl jewelry, each quality factor takes the grade that at least 90% of the pearls reach or exceed (§5.2.3.1).
Source & check 2026-09-26
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.18, §5.2.3.1, §5.2.3.2 Table 5, §6.7 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Cultured Pearl — quality factor (shape and size): Shape is graded by the percentage difference in diameter into four classes, round, oval, button and baroque, coded A1–A3, B1–B2, C1–C2 and D. Size is given as a diameter, or as the largest × smallest dimension.
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.2 and §6.3: maximum and minimum dimensions measured with a gauge graduated to 0.02 mm or finer; diameter-difference percentage X=(dmax−dmin)/d×100
- Qualification
The diameter-difference percentage limits of Table 1 differ between saltwater and freshwater cultured pearls; the two sets of limits are listed separately on the Saltwater cultured pearl and Freshwater cultured pearl pages.
Source & check 2026-09-26
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §4.2, §4.3 Table 1, §6.2, §6.3 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-26
Cultured Pearl — quality factor (colour): Color combines body color, overtone and iridescence. It falls into 7 series: white, red, yellow, black, gray, purple and other. These series cover various body colors.
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Measurement condition
- GB/T 18781—2023 §6.1: non-reflective grey or white background, away from brightly coloured objects, light source of colour temperature 5500 K–7200 K and colour rendering index above 90, pearl rolled and observed with the unaided eye
- Qualification
Registered under quality_factor/color (an attribute of the grading clause), not as the gem's own body colour; it is not an identity or naturalness determination. Iridescence is covered by a separate fact and is not described here.
Source & check 2026-09-17
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §3.7, §4.1.1, §6.1 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-17
Cultured Pearl — quality factor (minimum grades for jewellery grade): A pearl is jewelry grade only if all three reach their minimum level at the same time: luster medium (C), surface medium (D) and nacre thickness medium (D).
GB/T 18781—2023
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
All three minimums must be met at the same time: falling below any one of them makes it a craft-grade pearl (GB/T 18781—2023 §5.3).
Source & check 2026-09-20
- Source
- GB/T 18781—2023 Cultured pearl grading (GB/T): §5.2.1 (locator checked 2026-09-17)
- Fact checked on
- 2026-09-20
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Related CIBJO terms
- Bead for cultured pearls
a sphere (usually) or other shape (occasionally) originally formed by cutting and polishing a nacreous shell, usually from a freshwater bivalve, used to accommodate the nacre (5.126) secreted from a cultured pearl sac (5.54). The bead eventually forms the centre of a beaded cultured pearl (5.19). Atypically, beads formed from natural or cultured pearls of various types or other materials may be used, however, in such circumstances the product shall be described as containing an atypical bead or the type of bead shall be named, e.g., an “atypical bead cultured pearl”, a “turquoise bead cultured pearl”, a “coral bead cultured pearl”.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.18, p.23
- Beaded nacreous cultured pearl
beaded cultured pearls are usually nacreous (5.129) formations secreted in the interior of various saltwater and freshwater molluscs. A bead (5.18) is inserted into the mollusc along with a piece of mantle tissue which eventually forms the cultured pearl sac (5.54) around the bead which is in turn responsible for the secretion of nacreous layers. The outer layers of beaded nacreous cultured pearls are concentric and composed of a complex scleroprotein named conchiolin (5.49) and of calcium carbonate (usually in the form of aragonite). See nacreous cultured pearls (5.130).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.19, p.24
- Black cultured pearl
natural colour, cultured black pearl produced using either Pinctada margaritifera cumingii (9.58) (the Tahitian cultured pearl (5.195), Pinctada mazatlanica (9.61) or Pteria sterna (9.69) or other pearl oysters (5.158). The colour is not caused by any subsequent processing.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.23, p.24
- Cortez cultured pearl
trade name for the beaded cultured pearl produced in Pteria Sterna (9.69), the rainbow lipped pearl oyster, in the Gulf of California, Mexico, in an area also known as Sea of Cortez.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.51, p.27
- Culture
the growth of biological material, microorganisms, animal tissue or pearls with human intervention, in specially controlled conditions.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.52, p.27
- Cultured blister pearl
a cultured pearl that has perforated the mantle (freshwater) or the gonad cavity of the mollusc and has adhered, through layers of nacreous or non-nacreous secretions applied by the mollusc, to the inner wall of the shell. The subsequently formed layers of nacreous or non-nacreous material are continuous with those of the inner wall of the shell. They are round or irregular in shape and the base of the blister cultured pearl may be worked (5.210).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.53, p.27
- Cultured pearl sac
a pearl sac produced / grown from a graft (5.85) of mantle tissue (5.114) artificially inserted into the body of a host mollusc or created from mantle damage due to human handling.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.54, p.28
- Cultured pearls
cultured pearls are formed in the interior of productive living molluscs within a cultured pearl sac (5.54) with human intervention and a variety of conditions depending upon the mollusc and the goals. See 5.130, and 5.140.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.55, p.28
- Cultured conch pearls
cultured pearls formed in the interior of Aliger gigas (9.5) commonly known as Strombus gigas and sometimes Lobatus gigas, with human intervention and within a cultured pearl sac (5.54).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.56, p.28
- Fiji cultured pearl
cultured pearl produced in Pinctada margaritifera typica (9.59), that is produced in several colours in the Fiji Islands.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.69, p.29
- Gonad grown cultured pearl
a cultured pearl grown in the gonad (5.82) of a pearl producing mollusc.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.83, p.30
- Graft
a piece of epithelium tissue cut from the mantle (5.114) of a nacre (5.126) producing mollusc that is inserted into the body of another nacre producing mollusc (5.121), (usually of the same species), to initiate the growth of a cultured pearl sac (5.54) and a cultured pearl (5.55).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.85, p.30
- Grafting
the action of introducing tissue cut from the mantle (5.114) of a nacre (5.126) producing mollusc into the body of another nacre-producing mollusc (5.121) (usually of the same species) to initiate the growth of a cultured pearl sac (5.54) and thereafter a cultured pearl. Grafts can be implanted into the recipient molluscs mantle (5.114) or gonad (5.82) producing mantle-grown cultured pearls (5.115) or gonad-grown cultured pearls (5.83).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.86, p.30
- Gulf cultured pearl
a cultured pearl from the Arabian/Persian Gulf produced from the Pinctada radiata.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.90, p.31
- Hollow cultured pearl
a cultured pearl with a large enclosed cavity.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.98, p.31
- Mantle grown cultured pearl
a cultured pearl grown in the mantle (5.115) of a producing mollusc.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.115, p.34
- Mother-of-pearl bead
bead (round or irregular) carved from the thickest area of the smooth, hard, coating on the inner shell surface of some freshwater species, to produce a bead for pearl culturing farms around the world, most common species used e.g., Fusconia flava (9.23), Megalonaias nervosa (9.42 9.73), Quadrula quadrula (9.71), Reginaia ebenus (9.75) Other species used e.g., Amblema plicata (9.6), Cumberlandia monodonta (9.17), Cyclonaias tuberculate (9.18), Elliptio crasidens (9.20), and usually, but not always, some species produces natural pearls of same colour, and composition. In addition, from late 1800’s through 1960’s, these species produced commercial quantities of mother-of-pearl buttons in the USA.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.124, p.34
- Nacreous cultured pearls
pearls produced with or without the insertion by man of a bead (5.18) initially by grafting (5.86) mantle tissue that eventually forms a cultured pearl sac (5.54), which in turn produces the nacre necessary for the formation of a nacreous cultured pearl; the mollusc being maintained in culture until the pearl is harvested. Cultured pearl sacs (5.54) once produced may be re-used following the harvesting of cultured pearls to produce further beaded or non-beaded nacreous cultured pearls. Cultured pearls are usually nacreous (5.129), unattached formations, secreted within a cultured pearl sac (5.54) in the interior of pearl oysters (5.158) including Pinctada maxima (9.60), Pinctada margaritifera cumingii (9.58), Pinctada margaritifera typica 9.59, Pinctada mazatlanica (9.61), Pinctada fucata (9.54), Pinctada radiata (9.62), Pteria penguin (9.68), and Pteria sterna (9.69) as well as the freshwater mussels Cristaria plicata (9.16), Hyriopsis schlegeliii (9.32), Hyriopsis cumingii (9.31) and Megalonaias nervosa (9.42). The surfaces of nacreous cultured pearls are composed of nacre (5.126) that is laid down in concentric layers while within the cultured pearl sac (5.54). The secretion of the nacreous layers from the cultured pearl sac, within of the pearl oyster (5.158) is a natural process instigated and partially controlled by man. This applies to all cultured pearls whether grown with or without a bead (5.18). The term ‘cultured’ is applied to pearls that have been cultured (5.55) and is not applied to other pearls.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.130, p.35
- Non-beaded cultured pearl
a cultured pearl grown without a bead (5.18).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.139, p.38
- Non-nacreous cultured pearls
pearls produced with or without the insertion by human hand of a bead (5.18) by grafting (5.86), mantle tissue that eventually forms a cultured pearl sac (5.54), which in turn produces the calcium carbonate necessary for the formation of a non-nacreous cultured pearl; the mollusc being maintained in culture until the pearl is harvested. Cultured pearl sacs (5.54) once produced may be re-used following the harvesting of cultured pearls to produce further beaded or non-beaded non-nacreous cultured pearls. Non-nacreous Cultured pearls are unattached formations, secreted within a cultured pearl sac (5.56) in the interior of Aliger gigas (9.5) commonly known as Strombus gigas as well as sometimes Lobatus gigas (9.38) and are referred to as cultured conch pearls (5.48), which are non-nacreous pearls consisting of calcium carbonate arranged concentrically in a crossed lamellar microarchitecture. This structural characteristic usually produces a flame-like surface pattern and porcelaneous sheen. A natural process instigated and partially controlled by man forms the outer layers. This applies to all cultured non-nacreous cultured pearls whether grown with or without a bead (5.18). The term ‘cultured’ is applied to pearls that have been cultured (5.52) it is not applied to other pearls. Note: see Clause 2 Normative References; Convention on International Trade in Endangered Species of Wild Fauna and Flora.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.140, p.38
- Nucleus
a bead (5.18) around which a beaded cultured pearl (5.19) is formed. Bead is often round but is not limited to this shape, e.g. coin shape and the bead size may range from approximately 2 to 14mm depending on the species of mollusc used at cultured pearl farms.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.144, p.39
- Piece
a “piece” of mantle tissue (5.114).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.163, p.41
- Piece holder
tool to catch the graft (5.85) or mantle tissue (5.114) piece (5.163) for insertion during the grafting (5.86) procedure; also known as piece needle (5.165).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.164, p.41
- Piece process
a “piece” of mantle tissue from a donor mollusc is grafted, by human hand, into a host mollusc to begin the formation of a cultured pearl sac (5.54), the essential part of the culturing process (termed the “piece process”).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.166, p.42
Appearance and quality descriptors
- Nacre thickness
the thickness of nacre (5.126) overlaying the bead (5.18) in a beaded cultured pearl, usually expressed as an average in millimetres. Nacre thickness is only relevant in the case of beaded cultured pearls (5.19). It refers strictly to the thickness of the nacre covering the bead and may not be correlated with nacre quality, i.e., the nacre, whether “thick” or “thin”, may be of a variety of qualities. Nacre thickness is closely related to the culturing period and may have some impact on the colour, lustre and durability of the beaded cultured pearl (5.19).
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.127, p.35
- Nacre volume
expressed as a percentage of the total volume of a bead cultured pearl when excluding the bead.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.128, p.35
Fashioning, drilling and cleaning
- Carved
cultured pearl that has been engraved on the surface.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.34, p.25
- Cut cultured pearls
cultured pearls that have been cut in half or three quarters to produce a flat base.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.58, p.28
- Faceted cultured pearls
cultured pearls with multiple flat, convex or concave facets that have been artificially formed on their surface.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.67, p.29
Disclosure and documents
- Electronic tagging devices
Electronic devices such as RFID or NFC chips are sometimes inserted into cultured pearls. Their initial purpose may be for tagging or storing certain information, but sometimes the owners are not aware of their presence.
CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.65, p.29
Entries in the source that only point to another clause: Half composite cultured pearl (§5.91, p.31) → §5.58 Cut cultured pearls; Half cultured pearl (§5.93, p.31) → §5.58 Cut cultured pearls; Piece needle (§5.165, p.42) → §5.164 Piece holder; Three quarter cultured pearl (§5.201, p.45) → §5.58 Cut cultured pearls
Definitions are quoted verbatim from the cited CIBJO Blue Book; […] marks an excerpt, and the full definition is at the cited clause.
Pearl-producing molluscs (CIBJO Annex D): §9.5 Aliger gigas · §9.6 Amblema plicata · §9.16 Cristaria plicata · §9.17 Cumberlandia monodonta · §9.18 Cyclonaias tuberculata · §9.20 Ellipsaria lineolata · §9.23 Fusconaia flava · §9.31 Hyriopsis cumingii · §9.32 Hyriopsis schlegelii · §9.38 Lobatus gigas · §9.42 Megalonaias nervosa · §9.54 Pinctada fucata · §9.58 Pinctada margaritifera cumingii · §9.59 Pinctada margaritifera typica · §9.60 Pinctada maxima · §9.61 Pinctada mazatlanica · §9.62 Pinctada radiata · §9.68 Pteria penguin · §9.69 Pteria sterna · §9.71 Quadrula nodulata · §9.73 Quadrula quadrula · §9.75 Reginaia ebenus
Testing and market
Cultured Pearl has identification leads for dyeing, bleaching and irradiation. In dyed cultured pearls, magnification shows colour spots, with the colour mostly concentrated at growth defects; under long-wave and short-wave UV the dye may give a distinctive fluorescence. In Raman spectra, coloured freshwater pearls differ from dyed pearls; in UV-Vis spectra and laser photoluminescence spectra, coloured saltwater pearls differ from dyed pearls; chemical analysers such as XRF can detect foreign elements introduced by the dye, such as Ag; and luminescence image analysis shows that the fluorescence colour of dyed yellow saltwater pearls differs from that of untreated samples. In bleached cultured pearls, bleaching removes impurities from the surface of the nacre to improve colour and appearance, but is hard to detect. Irradiated cultured pearls may be black, greenish black, bluish black, grey and so on; magnification shows halo spots on the nacre layer caused by irradiation; and Raman spectra usually carry a very strong fluorescence background. The identification leads are cited from GB/T 16553—2017, which serves only as a reference for the cultured pearl entry and does not govern it directly.
How far testing can go
Cultured Pearl that has undergone dyeing can be identified by the following features: Magnification shows color patches, with the color mostly concentrated at growth defects; under long-wave and short-wave ultraviolet light the dye may show a distinctive fluorescence.
In spectroscopy, Raman spectra separate colored freshwater pearls from dyed pearls, while ultraviolet-visible and laser photoluminescence spectra separate colored seawater pearls from dyed pearls.
Compositional analysis (XRF and the like) can detect foreign elements introduced by the dye, Ag for instance; and luminescence imaging (an ultraviolet fluorescence viewer, for instance) shows that dyed yellow seawater pearls fluoresce in a color unlike that of untreated material.
GB/T 16553—2017
- Treatment state
- colour treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- dyeing
Source & check 2026-09-22
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (dyeing) (locator checked 2026-09-22)
- Fact checked on
- 2026-09-22
Cultured Pearl that has undergone bleaching can be identified by the following features: removes impurities from the surface of the cultured pearl's nacre layer to improve the colour and appearance; hard to detect.
GB/T 16553—2017
- Treatment state
- colour treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- bleaching
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (bleaching) (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Cultured Pearl that has undergone irradiation can be identified by the following features: Irradiation can turn pearl black, green-black, blue-black or grey; under magnification the nacreous layer shows irradiation halo spots, and Raman spectra mostly have a strong fluorescence background.
GB/T 16553—2017
- Treatment state
- irradiated or dyed
- Does this standard apply
- can be followed as a reference only
- Treatment
- irradiation
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.3.2 (irradiation) (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.
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.
- GIA – Gemological Institute of America (United States). Gem Encyclopedia: Pearl Description.
- CIBJO – The World Jewellery Confederation. The Pearl Book (Blue Book), 2024.
- 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 Pearl on this site: 17 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Cultured Pearl) is marked.
- Pearl
Sub-entries (16)
- Abalone Pearl
- Akoya Cultured Pearl
- Baroque Cultured Pearl
- Blister Pearl
- Circled Cultured Pearl
- Cultured Pearl
- Freshwater Cultured Pearl
- Freshwater Natural Pearl
- Keshi Cultured Pearl
- Natural Conch Pearl / Natural Melo Pearl
- Natural Pearl
- Saltwater Cultured Pearl
- Saltwater Natural Pearl
- South Sea Cultured Pearl
- Tahitian Cultured Pearl
- White South Sea Cultured Pearl
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Pearl and molluscan shell materials | Live |
| Treatments recorded for this material | Bleached, Dyed, Irradiated | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Cultured Pearl 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.