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Natural organic and biogenic materials · Organic or biogenic material · Natural identity; treatment status unknown

Pearl

Also known asCultured pearl (conditional name)

A general term for bead-like concretions formed by molluscs, covering natural and cultured, nacreous and non-nacreous pearls; trade names must specify each. 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 JuneReviewed by RalphLast updated 2026-10-12Who maintains this page

FAQCare and wear

Questions people ask about Pearl

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

Q1How is a real pearl told apart from an imitation?

It is a professional task: identifying a pearl as natural, cultured or imitation calls for trained gemmologists, and appearance alone cannot replace laboratory examination.GIA: How GIA Identifies PearlsGIA combines standard gemmological testing with instruments such as XRF, UV-Vis reflectance spectroscopy and real-time X-radiography to establish the pearl type, its mollusc and any detectable treatment.GIA: How GIA Identifies PearlsThe so-called tooth test was reported by GIA authors to separate gritty-feeling cultured pearls from one brand of smooth imitation, but the same authors warned that it can damage the pearl and that a gritty feel does not rule out other imitations.G&G Fall 1990Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer

Q2How do natural pearls differ from cultured ones?

The difference is human intervention: both are secreted by molluscs, but a natural pearl develops in mantle tissue, usually around a microscopic irritant, and never with human assistance.GIA Pearl DescriptionCultured pearls require human intervention: a shell bead and mantle tissue are implanted, and the mantle forms a nacre sac that secretes nacre in layers onto the bead.GIA Pearl Description · CIBJO Pearl Book 2024Some cultured pearls are grown without a bead, from several pieces of mantle tissue inserted into the mantle.GIA Pearl DescriptionMuseum catalogue records generally do not distinguish natural from cultured pearls.Cleveland Museum of Art 1928.234 · Cleveland Museum of Art 1947.507 +3

Q3What gives pearls their colour and glow?

The thickness and structure of the nacre govern lustre, while layered nacre and surface microstructure together produce the bodycolour and overtones.GIA Pearl DescriptionThe bodycolour is often modified by overtones such as pink, green, purple or blue, and some pearls show an iridescence known as orient.GIA Pearl Description · GIA Pearl Description (Chinese edition)Colour, size and shape depend on the mollusc species, the nacre thickness and the growing environment.GIA Pearl Description

Q4What makes a good-quality pearl?

Pearl quality turns on lustre, nacre thickness, surface condition, shape, colour, and how well the pearls in a strand match one another.CIBJO Pearl Book 2024 · GIA: How GIA Identifies PearlsGIA groups the factors as size and shape for bulk and outline, colour, nacre and lustre for appearance, and surface and matching for cleanliness and how a set hangs together.CIBJO Pearl Book 2024 · GIA: How GIA Identifies PearlsNacre thickness is a value factor: South Sea cultured pearls, for example, have thick nacre because of a long growth period.GIA Pearl Description · GIA Pearl Description (Chinese edition)

Q5Can you wear pearls every day?

With care: at Mohs 2.5 a pearl is very soft and scratches or abrades easily, and although its toughness is usually good, ageing, drying out or excessive bleaching can make some pearls more fragile.GIA Gem Encyclopedia (care guide)CIBJO advises avoiding rough handling and not wearing pearls during heavy work.CIBJO Pearl Book 2024Pearls are usually pin-set; prong settings call for caution, bezel for extreme caution, and flush, channel and pavé are best avoided, as thin nacre may chip or fracture easily.Gems & Gemology 1987 (Martin)When not worn, pearls should be kept apart from other jewellery to avoid scratches and not wrapped in moisture-absorbing materials such as cotton wool.CIBJO Pearl Book 2024

Q6How should you clean pearls, and what damages them?

Wipe pearls with a very soft clean cloth after each wear; for an occasional thorough clean, warm soapy water is safe, but a strand's thread must dry completely before wearing, and steam cleaning should never be used.GIA Gem Encyclopedia (care guide)Ultrasonic cleaning must not be used.CIBJO Pearl Book 2024Many chemicals and every acid can damage pearls, including hair spray, perfume, cosmetics and even sweat.GIA Gem Encyclopedia (care guide)Cosmetics should be applied before pearls are put on, not after.CIBJO Pearl Book 2024High heat can burn cultured pearls, or discolour or crack them.GIA Gem Encyclopedia (care guide)GIA's general jewellery-care guidance says fine jewellery should come off before a dip in a chlorinated pool or the use of household cleaners, and that hairspray, lotion, perfume and other cosmetics can permanently damage a pearl's surface.GIA jewellery care tips

Q7Are pearls dyed or treated, and do the treatments last?

Yes: pearls may be coated, dyed, filled, irradiated, lustre-enhanced, oiled or resin-treated, tinted or waxed, and apart from irradiation none of these treatments is permanent whatever care is taken; bleaching may not be permanent either.CIBJO Pearl Book 2024GIA notes that dyeing, impregnation and coating may change over time, while bleaching and irradiation can be stable in normal wear.GIA Gem Encyclopedia (care guide)Some colour-treated pearls may fade or revert to their original colour under sunlight, artificial light or strong display lights.CIBJO Pearl Book 2024Detectable treatment is established in the laboratory, alongside the pearl type and its mollusc.GIA: How GIA Identifies Pearls

Q8How does a pearl form inside a mollusc?

Pearl is a biogenic organic gem material secreted by certain molluscs such as pearl oysters and mussels; it does not form by geological crystallization.GIA Pearl DescriptionCells of the mantle form a nacre sac around the irritant or implant and secrete nacre inward.GIA Pearl DescriptionNacre is deposited layer by layer, building up thickness over time until the pearl forms.GIA Pearl DescriptionThe source gives no absolute timescale for pearl growth.GIA Pearl Description

Q9What is the difference between Akoya, South Sea, Tahitian and freshwater pearls?

Akoya cultured pearls are saltwater pearls from Japan and China, while South Sea cultured pearls are saltwater pearls mainly from Australia, Indonesia and the Philippines and range from white to silver or golden.GIA Pearl DescriptionTahitian cultured pearls are saltwater pearls grown mainly around French Polynesia, sometimes called black pearls and grey, black or brown, while freshwater cultured pearls are usually grown in lakes and ponds, often many in one mollusc, with China the leading source.GIA Pearl Description

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

There is no scientific evidence that pearl 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 June birthstone: Jewelers of America and Japan's JJA list it for June, and the U.K. National Association of Jewellers lists it as traditional for June.Cultural recordsAn early pearl-bearing ornament in a museum collection is a Greek necklace from the 100s BCE that includes a baroque pearl.Cleveland Museum of Art 1928.234 · Cleveland Museum of Art 1947.507 +3

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

Pearl is a biogenic organic gem material secreted by certain mollusks such as pearl oysters and mussels; it does not form by geological crystallization. A natural pearl develops inside the mantle tissue of some mollusks, generally about a microscopic irritant, and never with human assistance. Cultured pearls, by contrast, need human intervention: a technician inserts a shell bead together with a small piece of mantle tissue into the host mollusk's gonad, or several pieces of mantle tissue without beads into its mantle, after which the mantle forms a sac and secretes nacre inward and onto the bead, building the pearl layer by layer. Colour, size and shape therefore depend on the mollusk species, the nacre thickness and the growing environment.

Scope: Covers the general origin of natural pearls and of saltwater and freshwater cultured pearls; does not apply to imitation pearls such as glass or plastic, nor to blister pearls.

Sources GIA Pearl Description

Where it forms

The organic secretory microenvironment inside a mollusk (mantle tissue or gonad)

Sources GIA Pearl Description

Marine or freshwater farm waters that match the host mollusk's natural habitat

Sources GIA Pearl Description

How it forms, step by step

  1. An irritant or implant enters the mollusk: in natural pearls a microscopic irritant is enclosed within mantle tissue; in cultured pearls a technician inserts a shell bead with a small piece of mantle tissue into the gonad, or several mantle-tissue pieces into the mantle.

    Sources GIA Pearl Description

  2. The mantle epithelial cells form a nacre sac around the implant and secrete nacre inward and onto the bead or tissue.

    Sources GIA Pearl Description

  3. Nacre is deposited layer by layer, accumulating thickness over time until the pearl forms; cultured pearls are tended until harvest.

    Sources GIA Pearl Description

Link to appearance

Nacre thickness and structure govern luster; layered nacre and surface microstructure together produce bodycolor and overtones, and some pearls show the iridescent phenomenon known as orient.

Sources GIA Pearl Description

Timescale

The source gives no absolute timescale for pearl growth; it only describes a long growth period as a factor in nacre thickness and value.

Sources GIA Pearl Description

Supporting findings

Pearl — whether natural or cultured — is a biogenic material secreted by mollusks; a natural pearl develops in mantle tissue, usually about a microscopic irritant, and never with human assistance.

Evidence grade B

Scope: Applies to natural molluscan pearls; not to plastic or glass imitations.

Sources GIA Pearl Description

Cultured pearls require human intervention: a shell bead and mantle tissue are implanted, and the mantle forms a nacre sac that secretes nacre in layers onto the bead.

Evidence grade A

Scope: Describes the standard beading/tissue-grafting culture process, not every operational variant.

Sources GIA Pearl Description · CIBJO Pearl Book 2024

Recorded localities

This is an organic material; its localities are the harvest or culture areas (waters or species ranges) recorded by authoritative sources.

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).

Asia

  • JapanOrganic harvest or culture areaAkoya cultured pearls
    Sources GIA Pearl Description
  • ChinaOrganic harvest or culture area · Principal sourceLeading source of freshwater cultured pearls; also produces akoya
    Sources GIA Pearl Description
  • IndonesiaOrganic harvest or culture area · Principal sourceA leading source of South Sea cultured pearls
    Sources GIA Pearl Description
  • PhilippinesOrganic harvest or culture area · Principal sourceA leading source of South Sea cultured pearls
    Sources GIA Pearl Description
  • MyanmarOrganic harvest or culture areaPinctada maxima cultured pearls
    Sources GIA Pearl Description

Oceania

  • AustraliaOrganic harvest or culture area · Principal sourceA leading source of South Sea cultured pearls
    Sources GIA Pearl Description
  • French PolynesiaOrganic harvest or culture area · Principal sourceMain area for Tahitian cultured pearls
    Sources GIA Pearl Description

These are localities recorded by authoritative sources, not an origin finding for any individual piece. The CIBJO Gemstone Book (2022, §4.2.3) says a place of origin names where a gem was mined or harvested, is a matter of opinion, does not imply a level of quality, and that cutting, processing or exporting centres must not be used to imply origin. See how far testing can go on this page, the origin determination guide and the overview of recorded localities.

Causes of colour and optical effects

A pearl's bodycolor is often modified by overtones such as pink, green, purple, or blue, and some pearls show the iridescent phenomenon known as orient.

Evidence grade A

Scope: The source describes the phenomenon but does not explain the specific optical cause of orient.

Sources GIA Pearl Description · GIA Pearl Description (Chinese edition)

Human use and museum objects

An early pearl-bearing ornament is Cleveland 1928.234, a necklace (100s BCE, Greece) of gold, moonstone, garnet, emerald, cornelian, baroque pearl and banded agate; it shows pearls used as a jewellery-setting material in the ancient Mediterranean.

Evidence grade A

Scope: Catalogue objects attest only to the existence and dating of those individual pieces; they are not evidence that the material was in common use in antiquity, nor do they attest to the origin, naturalness or treatment of any modern sample. Cultural attributions follow the museum's records and are not extended.

Sources Cleveland Museum of Art 1928.234 · Cleveland Museum of Art 1947.507 · Cleveland Museum of Art 2001.156 +2

Pearls also appear in medieval-to-modern European and Chinese ornaments, e.g. Cleveland 1947.507 (c. 1400, Paris), 2001.156 (c. 1850, England) and The Met 2003.350.2 (1845–50); but catalogue metadata generally does not distinguish natural from cultured pearls, so this evidence states the existence and dating of pearl ornaments, not their natural origin.

Evidence grade A

Scope: Catalogue objects attest only to the existence and dating of those individual pieces; they are not evidence that the material was in common use in antiquity, nor do they attest to the origin, naturalness or treatment of any modern sample. Cultural attributions follow the museum's records and are not extended.

Sources Cleveland Museum of Art 1928.234 · Cleveland Museum of Art 1947.507 · Cleveland Museum of Art 2001.156 +2

Among the catalogue objects, an early pearl-bearing ornament is Cleveland 1928.234, a necklace (100s BCE, Greece) of gold, moonstone, garnet, emerald, cornelian, baroque pearl and banded agate. Pearls recur in 1947.507 (c. 1400, Paris; enameled gold, gems and pearls, some later additions), 2001.156 (c. 1850, England; seed pearls on mother-of-pearl), The Met 2003.350.2 (1845–50; seed pearls, mother-of-pearl and more) and Cleveland 1945.167 (1800s, Qing China; tourmaline, jade, pearls and more). Note: the cited collections also include many artworks on the theme of pearls (prints, painted portraits); these attest to pearls' visual depiction, not to the objects themselves, so only the ornaments above are used as physical evidence.

Sources Cleveland Museum of Art 1928.234 · Cleveland Museum of Art 1947.507 · Cleveland Museum of Art 2001.156 +2

Scope: Catalogue objects attest only to the existence and dating of those individual pieces; they are not evidence that the material was in common use in antiquity, nor do they attest to the origin, naturalness or treatment of any modern sample. Cultural attributions follow the museum's records and are not extended.

Objects cited

500 BCE0500100015002000CMA 1928.234100s BCECMA 1947.507c. 1400CMA 1945.1671800sMet 2003.350.21845–50CMA 2001.156c. 1850
Dates of museum objectsDates from the museums' open-access records (CC0); each bar spans the whole period named in the record, with qualifiers such as “early” or “possibly” kept in the label rather than turned into a narrower range; an arrow marks a record that reads “before” or “after” a yearSource: The Met / Cleveland Museum of Art open-access records

Cultural records for this material: Birthstone list.

How it is identified

Identifying a pearl — natural, cultured or imitation — is a professional task. GIA routes each item to trained gemologists who combine standard gemological testing with advanced instruments — among them XRF, UV-Vis reflectance spectroscopy and real-time X-radiography — to establish the pearl type, its mollusc and any detectable treatment; when needed, real-time microradiography gauges the nacre thickness of bead-cultured pearls, and computed micro-tomography (μCT) can add further detail. Appearance alone cannot replace this laboratory examination.

Evidence grade A

Scope: Applies to pearl identification and classification; it must be done by a trained professional body following procedure, and is not a self-identification method.

Sources GIA: How GIA Identifies Pearls

The 'tooth test' — rubbing a pearl gently against the edge of the front teeth — was reported by GIA authors to separate cultured pearls, which feel gritty, from one brand of imitation, which felt smooth. The same authors warned that the test can be damaging and that a gritty feel does not rule out other imitations, since manufacturers can make imitations with a gritty surface.

Evidence grade A

Scope: Reports what one laboratory study said about the tooth test; it is not a recommendation to use it, and only a gemmological laboratory can establish whether a pearl is natural, cultured or imitation.

Sources G&G Fall 1990

Other research findings

Nacre thickness is a value factor: South Sea cultured pearls have thick nacre because of a long growth period, and their limited growing conditions also contribute to their value.

Evidence grade A

Scope: Concerns cultured-pearl value factors using South Sea pearls as the example, not formation mechanism.

Sources GIA Pearl Description · GIA Pearl Description (Chinese edition)

Pearl quality turns on lustre, nacre thickness, surface condition, shape, colour, and how well the pearls in a strand match one another. GIA collects the relevant factors into seven groups: size and shape speak to a pearl's bulk and outline; colour, nacre and lustre to its appearance; surface and matching to cleanliness and how a set hangs together.

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. Pearl quality assessment must be issued by an accredited laboratory for a specific specimen.

Sources CIBJO Pearl Book 2024 · GIA: How GIA Identifies Pearls

GIA's jewellery-care guidance says fine jewellery should be taken off before diving into a chlorinated swimming pool or using household cleaners, and that everyday substances such as hairspray, lotion, perfume or other cosmetics can contain chemicals that permanently damage the surface of pearls.

Evidence grade B

Scope: Reports one educational source's general care guidance; the swimming-pool sentence refers to fine jewellery in general rather than to pearls alone, and no source found addresses showering with pearls specifically.

Sources GIA jewellery care tips

Akoya cultured pearls are saltwater pearls produced in Japan and China. South Sea cultured pearls are saltwater pearls whose leading sources are Australia, Indonesia and the Philippines; depending on the oyster they range from white to silver or golden.

Evidence grade B

Scope: Summarises one educational source's overview of pearl types; colours and sources are typical, not limits, and the type of any single pearl can only be established by laboratory testing.

Sources GIA Pearl Description

Tahitian cultured pearls are saltwater pearls cultivated mainly around the islands of French Polynesia and are sometimes called black pearls; they may be grey, black or brown. Freshwater cultured pearls are usually grown in freshwater lakes and ponds, often many pearls in one mollusc, and China is the leading source.

Evidence grade B

Scope: Summarises one educational source's overview of pearl types; colours and sources are typical, not limits, and the type of any single pearl can only be established by laboratory testing.

Sources GIA Pearl Description

Limits of this research

  • Research status: Formation, occurrence or other material-specific findings found in authoritative sources
  • The source is an institutional educational page and gives no absolute timescale for pearl growth.
  • Orient is described only as a phenomenon; its optical cause is not explained in this source.

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
Pearl (natural or cultured status and type must be stated)

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

Natural identity; treatment status unknown

Treatments recorded for this material: Bleached, Coated, Dyed (via parent material), Irradiated (via parent material)

Related:Disclosure and cautions

This page cannot answer

Natural? · Origin · Price

A lab report settles these; this wiki covers naming and disclosure.

Related:What this page can answer

Answer at a glance

Pearl (generic heading—specify natural or cultured) is often subjected to bleaching and coating. Under GB/T 16552-2017, bleaching counts as an optimization, so the plain gem name may be used (§5.4.2.1 a); coating is graded by the material used, and must be stated in the name wherever it counts as a treatment (§5.4.1, Table 1). Do not assume it is unenhanced.

Evidence

  • CIBJO · 4.4.1.1.2

What this means for you

Before buying, check the recommended listing name "Pearl (natural or cultured status and type must be stated)" 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
  • Disclosure rules for the treatments above can change as authorities update their standards; re-check before relying on this page.
Last reviewed
2026-09-01

Trade-name ruling

  • Laboratory identification required before the name is used.
Suggested listing name
Pearl (natural or cultured status and type must be stated)

Care and wear

Care

care (cleaning)3 sources compared

Pearl — care (cleaning): Wipe with a soft cloth dampened in clean water after wear, and wipe regularly as well when it is not worn for long periods; no ultrasonic cleaning.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.1, §7.2 (Annex B, normative), p.49 (locator checked 2026-09-17)
Fact checked on
2026-09-17

Pearl — care (cleaning): Never steam-clean it either; for an occasional thorough clean warm soapy water is safe, but let a strand's thread dry completely before wearing; routinely wipe it with a very soft clean cloth after each wear.

GIA Gem Encyclopedia (care guide)

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

Pearl — care (cleaning): ultrasonic and steamer: avoid; note: wash gently in warm soapy water, dry thoroughly and restring.

Gems & Gemology 1987 (Martin)

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

care (heat)2 sources compared

Pearl — care (heat): Do not expose it to high temperatures

CIBJO Pearl Book 2024

Treatment state
any treatment state
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.2 (Annex B, normative), p.49 (locator checked 2026-09-17)
Fact checked on
2026-09-17

Pearl — care (heat): High heat can burn cultured pearls, or discolour or crack them.

GIA Gem Encyclopedia (care guide)

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

care (light)2 sources compared

Pearl — care (light): Colour may fade or change if exposed to long periods of sunlight or short exposures to x-rays.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Applies only to
natural and cultured conch pearls
Source & check 2026-09-26
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §4.3.1, p.14; §7.2.2 note, p.49 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Pearl — care (light): Colour may fade or change if exposed to long periods of sunlight or chemicals.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Applies only to
coloured natural and cultured pearls
Source & check 2026-09-26
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §4.3.1, p.14 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Pearl — care (light): The colour of some natural and cultured pearls may fade when exposed to natural sunlight, artificial light or strong display lights.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.2.2 (Annex B, normative), p.49, 1st sentence (locator checked 2026-09-17)
Fact checked on
2026-09-17

Pearl — care (light): generally stable in light, but heat from intense light can dry it out and crack the nacre.

GIA Gem Encyclopedia (care guide)

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

Pearl — care (light): should not be left for long periods in strong natural or artificial light or under strong display lighting.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Applies only to
pearls that fade or revert to their original colour
Source & check 2026-09-26
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.2.2 (Annex B, normative), p.49, 3rd sentence (locator checked 2026-09-26)
Fact checked on
2026-09-26

Pearl — care (light): Some natural and cultured pearls that have been colour treated may fade or revert to their original colour when exposed to natural sunlight, artificial light or strong display lights.

CIBJO Pearl Book 2024

Treatment state
colour treated
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.2.2 (Annex B, normative), p.49, 2nd sentence (locator checked 2026-09-17)
Fact checked on
2026-09-17

care (chemicals)2 sources compared

Pearl — care (chemicals): Cosmetics should be applied before, not after, pearls are put on; keep away from all solvents and acids.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.1, §7.2 (Annex B, normative), p.49 (locator checked 2026-09-17)
Fact checked on
2026-09-17

Pearl — care (chemicals): Dyeing, impregnation and coating may change over time; bleaching and irradiation can be stable in normal wear.

GIA Gem Encyclopedia (care guide)

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

Pearl — care (chemicals): Many chemicals and every acid can damage it, including hair spray, perfume, cosmetics and even sweat.

GIA Gem Encyclopedia (care guide)

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

Pearl — care (storage): When not worn, store apart from other jewellery to avoid scratches; do not wrap in moisture-absorbing materials such as cotton wool.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.1 (Annex B, normative), p.49 (locator checked 2026-09-17)
Fact checked on
2026-09-17

care (wear)2 sources compared

Pearl — care (wear): Avoid rough handling; should not be worn while carrying out heavy work.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Source & check 2026-09-17
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.1, §7.2 (Annex B, normative), p.49 (locator checked 2026-09-17)
Fact checked on
2026-09-17

Pearl — care (wear): break easily, so they are not meant for everyday wear and should not be worn during heavy work; natural abalone pearls are often hollow and therefore fragile.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Applies only to
abalone pearls, natural blisters and some cultured blisters
Source & check 2026-09-26
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §7.2.1 and note (Annex B, normative), p.49; §4.3.1, p.14 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Pearl — care (wear): At Mohs 2.5 it is very soft and scratches or abrades easily; toughness is usually good, but ageing, drying out or excessive bleaching during initial processing can make some pearls more fragile.

GIA Gem Encyclopedia (care guide)

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

Pearl — care (wear): natural and cultured pearls that have a large percentage of organic material within their structures are often fragile.

CIBJO Pearl Book 2024

Treatment state
any treatment state
Applies only to
natural and cultured pearls rich in organic material
Source & check 2026-09-26
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §4.3.1, p.14 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Pearl — care (special care): coating, dyeing, filling, irradiation, lustre enhancement, oil or resin, tinting and waxing call for special care (the trade code carries SC); apart from irradiation, none of these treatments is permanent whatever special care is taken, and bleaching may not be permanent either.

CIBJO Pearl Book 2024

Treatment state
treated
Source & check 2026-09-26
Source
  • CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §6.1 table (Annex A, normative), p.48; §4.3.2, p.14 (locator checked 2026-09-26)
Fact checked on
2026-09-26

Pearl — care (setting): prong: use caution; bezel: use extreme caution; flush, channel and pavé: avoid; note: usually pin-set; thin nacre may chip or fracture easily.

Gems & Gemology 1987 (Martin)

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

Pearl — care (repair): jeweller's torch, pickle pot, polishing and thermal shock: avoid; note: avoid heat, which cracks it and may turn it brown, burn it or split it; every acid attacks it.

Gems & Gemology 1987 (Martin)

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

Pearl — care (display): dyed pearls: some colours may fade.

Gems & Gemology 1987 (Martin)

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

Pearl — care (display): artificial light: use caution; heat in the display case and sunlight: avoid; note: moderate heat and strong light speed up dehydration and cracking.

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

CleaningCleaning Pearl: in any treatment state, CIBJO states to wipe it after wearing with a soft cloth dampened in clean water, and to wipe it regularly even when it is not worn for long periods, and that ultrasonic cleaning is prohibited; GIA states that it must never be steam-cleaned, that warm soapy water can be used for an occasional thorough clean, and that a strand should not be worn until its thread is completely dry. Heat: in any treatment state, CIBJO states it must not be exposed to high temperatures, and GIA states that high heat can burn cultured pearls or cause them to discolour or crack. Chemicals: in any treatment state, CIBJO states that cosmetics should be applied before putting on pearls and that pearls should be kept away from all solvents and acids; GIA states that many chemicals and all acids damage pearls, including hairspray, perfume, cosmetics and even perspiration. Light: in any treatment state, CIBJO states that some natural and cultured pearls may fade under sunlight, artificial light or strong display lighting; GIA states that pearls are generally stable to light but the heat of strong light can dry them out and crack the nacre. Wear: in any treatment state, GIA states that at Mohs 2.5 Pearl is very soft and easily scratched and abraded; CIBJO states to avoid rough handling and not to wear pearls during heavy manual work.

This table scrolls sideways on narrow screens.

QuestionMatching entries
Can it go in an ultrasonic or steam cleaner?Wipe with a soft cloth dampened in clean water after wear, and wipe regularly as well when it is not worn for long periods; no ultrasonic cleaning; Never steam-clean it either; for an occasional thorough clean warm soapy water is safe, but let a strand's thread dry completely before wearing; routinely wipe it with a very soft clean cloth after each wear; ultrasonic and steamer: avoid; note: wash gently in warm soapy water, dry thoroughly and restring
Heat and thermal shockDo not expose it to high temperatures; High heat can burn cultured pearls, or discolour or crack them; jeweller's torch, pickle pot, polishing and thermal shock: avoid; note: avoid heat, which cracks it and may turn it brown, burn it or split it; every acid attacks it
Light and displaynatural and cultured conch pearls: care (light); coloured natural and cultured pearls: care (light); care (light); generally stable in light, but heat from intense light can dry it out and crack the nacre; pearls that fade or revert to their original colour: should not be left for long periods in strong natural or artificial light or under strong display lighting; care (light); dyed pearls: some colours may fade; artificial light: use caution; heat in the display case and sunlight: avoid; note: moderate heat and strong light speed up dehydration and cracking
Contact with acids, alkalis and household chemicalsCosmetics should be applied before, not after, pearls are put on; keep away from all solvents and acids; Dyeing, impregnation and coating may change over time; bleaching and irradiation can be stable in normal wear; Many chemicals and every acid can damage it, including hair spray, perfume, cosmetics and even sweat
Wearing limits (knocks, settings)Avoid rough handling; should not be worn while carrying out heavy work; abalone pearls, natural blisters and some cultured blisters: break easily, so they are not meant for everyday wear and should not be worn during heavy work; natural abalone pearls are often hollow and therefore fragile; At Mohs 2.5 it is very soft and scratches or abrades easily; toughness is usually good, but ageing, drying out or excessive bleaching during initial processing can make some pearls more fragile; natural and cultured pearls rich in organic material: care (wear); prong: use caution; bezel: use extreme caution; flush, channel and pavé: avoid; note: usually pin-set; thin nacre may chip or fracture easily

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.

any treatment state

untreated

colour treated

treated

treated (Only after these treatments: coating, dyeing, impregnation)

treated (Only after these treatments: dyeing)

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)

How lab reports word it

Pearl — how lab reports word it (multi-pearl submissions): For lots of more than twenty where over a fifth are cultured but many cannot be tested one by one, reports first give only this line; per-pearl results need the pearls taken apart.

LMHC Pearl Information Sheet #1

Wording on the report: Contains cultured pearls

Case
more than twenty pearls, over a fifth found cultured
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — how lab reports word it (multi-pearl submissions): When fewer than a fifth are cultured, the report gives the number and positions of the cultured pearls and says nothing about the rest.

LMHC Pearl Information Sheet #1

Wording on the report: cultured pearls at positions

Case
more than twenty pearls, under a fifth found cultured
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — how lab reports word it (multi-pearl submissions): When a strand consists entirely of pearls under about 3 mm, the report gives only this name and states that they may be natural or cultured; the sheet gives the size limit in two slightly different ways.

LMHC Pearl Information Sheet #1

Wording on the report: Seed Pearls

Case
strands of pearls under about 3 mm
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

VerifyNames, standards, technical facts, clauses and sources

Names

Besides Pearl, the name register records "Cultured pearl", for which no restriction on use as a name is recorded (CIBJO Pearl Book 2024 §4.4.1.1.2; 16 CFR Part 23 §23.20(b)).

Standard and listing namesThe GB/T 16552—2017 formal name of Pearl comes from the “Cultured pearl (pearl)” row of Table A.3; the suggested listing name is Pearl (natural or cultured, and type, must be stated). Candidate search termsThe trade name or synonym is recorded as Cultured pearl, which the name register lists as an English narrower name, a search candidate only; the related high-risk name is Pearl. Names in four languagesThe four-language names are the Simplified and Traditional Chinese names, English Pearl (as a category term, natural or cultured must be stated) and the Japanese name (with natural or cultured stated); the GSJ (Japan) formal name is the Japanese word for pearl. Institution usageOf GIA, FTC, CIBJO and Gem-A, this site records only the wording of FTC and CIBJO, which is Pearl; GIA and Gem-A are unchecked. The qualifier stripped from the headline name, that as a category term natural or cultured must be stated, comes from the entry's own English name and does not represent GIA or Gem-A wording. National standard namesThe formal name in India (BIS) is Pearl or Moti (मोती), and cultured pearls must be disclosed. Trade and mineralogical namesThe mineralogical name describes pearl as a collective term for mollusc concretions, natural and cultured, nacreous and non-nacreous.

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)
Cultured pearlEnglishnarrower name (variety or subtype)search candidate onlyno restriction recordedCIBJO Pearl Book 2024 4.4.1.1.2; 16 CFR Part 23 §23.20(b); Note: Related high-risk name “Pearl”.

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

Authority wording

GIA, FTC, CIBJO, Gem-A
Pearl (on record for FTC, CIBJO (16 CFR Part 23 §23.20; CIBJO Gemmological Laboratories Book 2024 §7.2.2.9); GIA, Gem-A unchecked — bodies without a recorded wording show the entry's own English name)
GSJ (Japan) formal name
真珠
Chinese formal name
珍珠 (GB/T 16552—2017 Table A.3, row “Cultured Pearl(Pearl)”)
Mineralogical name
Generic term covering natural and cultured molluscan concretions; nacreous or non-nacreous
Trade names and synonyms
Cultured pearl (narrower name (variety or subtype); conditional name)

Four-language names

简体中文
珍珠
繁體中文
珍珠
English
Pearl (generic heading—specify natural or cultured)
日本語
真珠（天然／養殖を明記）

National and regional formal names

India (BIS)
Pearl / Moti (मोती); cultured must be disclosed

Qualifiers stripped from the headline name

  • GIA, Gem-A (not yet checked; this qualifier is part of the entry's own English name): (generic heading—specify natural or cultured)

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
Natural identity; treatment status unknown

Treatments listed by standards

On this site, Pearl is covered by both the Natural Pearl row and the Cultured Pearl (Pearl) row of Table B.1 in Annex B of GB/T 16552—2017: under the Natural Pearl row, bleaching is listed as optimization and dyeing as treatment; under the Cultured Pearl (Pearl) row, bleaching is listed as optimization, dyeing as treatment and irradiation as treatment. GB/T 16552—2017 allows cultured pearl to be shortened to pearl, and the word pearl in the Cultured Pearl (Pearl) row of Table B.1 is that short form for cultured pearl; on this site Pearl is the umbrella entry for both natural and cultured pearls, so both the Natural Pearl row and the Cultured Pearl (Pearl) row apply. For what Table B.1 is and how each grade is defined, see this site's Gem treatments page.

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

  • Under the “Natural Pearl” row of Table B.1: Bleaching Optimization; Dyeing Treatment. The full row, with the effect column, is on the Natural Pearl page.
  • Under the “Cultured Pearl (Pearl)” row of Table B.1: Bleaching Optimization; Dyeing Treatment; Irradiation Treatment. The full row, with the effect column, is on the Cultured Pearl page.

GB/T 16552-2017 clause 5.1.2.3 b) allows cultured pearl to be shortened to “pearl”; the “Cultured Pearl (Pearl)” row of Table B.1 uses that short form. This site’s Pearl entry covers both natural and cultured pearls, so both rows are listed.

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 Mohs hardness of Pearl is registered as 2.5–3. The registered stability states that, when untreated, it should be kept away from all solvents and acids, must not be exposed to high heat, must not be cleaned ultrasonically, and should not be worn during heavy physical work. On optics and appearance, orient is the optical phenomenon of soft iridescent spectral hues produced by the interference and diffraction of light just beneath the surface of certain nacreous pearls; lustre is the quality and quantity of light reflected from or near the surface of a natural or cultured pearl; colour has three attributes, hue, tone and saturation, and the colour of nacreous natural and cultured pearls can generally be described as a combination of body colour, overtone and orient, body colour being the dominant overall colour and overtone an additional or secondary colour, usually pink, green or blue; shape or outline falls broadly into round, near-round, oval, button, drop and baroque.

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”.

Durability

Pearl — Mohs hardness: 2.5–3

GIA Gem Encyclopedia

123456789102.5–3References (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, 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))

Mohs hardnessSource: GIA Gem Encyclopedia
Source & check 2026-09-20
Source
Fact checked on
2026-09-20

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

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

Related CIBJO terms

Adductor muscle

the muscle attached to both valves of a bivalve (5.21) that causes the shell to close when it contracts.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.3, p.22

Alteration

any change made to a pearl, cultured pearl or artificial products.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.8, p.22

Bivalve

a member of the molluscan class Bivalvia, having a two-part shell, e.g., clam, oyster, mussel, and scallop.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.21, p.24

Chemically altered

a treatment that changes the colour of a pearl or cultured pearl without the use of a dye.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.38, p.25

Gem

Another term, often used as an adjective, to describe an exceptional pearl or cultured pearl noting perfection or very high quality. NOTE – the term “Gem” shall only be used to qualify the terms “real”, “precious”, “genuine” and “natural”.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.79, p.30

Gonad

the sex or reproductive organ.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.82, p.30

Invertebrate

an animal without an internal backbone. Examples are snails (gastropods) and clams (molluscs), crabs and shrimp (crustaceans), starfish and sea urchins (echinoderms), worms (annelids), corals and sea fans (cnidarians).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.101, p.32

Lustre enhancement

any treatment, other than polishing, applied to enhance the lustre of a natural or cultured pearl, e.g., “maeshori” (5.113).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.111, p.33

Maeshori treatment

a multi-part chemical treatment, including exposure to heat and/or light, that temporarily enhances lustre.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.113, p.33

Mantle

the mantle is an organ found in molluscs. It is the dorsal body wall covering the main body, or visceral mass. The outer epidermis (surface towards the shell) of this organ secretes calcium carbonate to create a shell.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.114, p.33

Marine gastropod

a univalve mollusc that lives in the sea, e.g., see clauses (9.12, 9.38, 9.43, and 9.47).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.116, p.34

Mollusc

an invertebrate (5.101) animal of the phylum Mollusca.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.121, p.34

Optical brightening

Also sometimes known as fluorescence whitening, optical brightening agents (OBAs) are chemical compounds that can absorb light in the ultraviolet and violet region of the electromagnetic spectrum and emit light in the blue region as fluorescence. The use of OBAs in the cultured pearl industry is not unusual and they are sometimes routinely applied to cultured pearls post-harvest.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.149, p.40

Orient

an optical phenomenon caused by the interference and diffraction of light from within the surface of some nacreous pearls; producing delicate shades of iridescent spectral colours.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.151, p.40

Oyster

a common name applied to a number of bivalved molluscs (5.21) (Kai in Japanese), some of them not closely related. Pearl oysters are of the family Pteriidae. True (edible) oysters are of the family Ostreidae.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.154, p.40

Pearl oyster

marine bivalves classified in the family Pteriidae and the genera Pinctada and Pteria, e.g., Pinctada maxima (9.60), Pinctada margaritifera cumingii (9.58), Pinctada margaritifera typica (9.59) Pinctada mazatlanica (9.61), Pinctada fucata (martensii) (9.57), Pinctada imbricata (9.55), Pinctada radiata (9.62), Pinctada maculata (9.56),Pteria penguin (9.68), and Pteria sterna (9.69).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.158, p.41

sp. or ssp.

sp. - taxonomic notation for undetermined species of the given genus (e.g. Pinctada sp. - undetermined species of the genus Pinctada).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.188, p.44

Spat

saltwater larval molluscs (5.121) that have settled on a hard substratum, to grow to adulthood or glochidia the freshwater larval molluscs that attach themselves to certain species of freshwater fish gills until their hard shell has developed.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.189, p.44

spp.

spp. - taxonomic notation for all species from the given genus (e.g. Haliotis spp. all species of the genus Haliotis).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.192, p.44

Tinting

a treatment which causes a subtle change in colour and/or appearance (often associated with bleaching).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.202, p.46

Weights, grading sieves and pricing

Carat

a unit of weight (5.209), one carat being equivalent to 200 milligrams (1/5 gram).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.33, p.25

Chaw

system of converting weight into volume. Pearls in the Arabian Gulf and India are often sold by chaw. The formula for calculating the weight in Chaw is; multiply the carat weight by itself and then multiply by 0.6518.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.36, p.25

Grain

a unit of weight often used in the trade to approximate the weight of a natural pearl, a grain is equal to 0.25ct.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.87, p.31

Gram

1/1000 of a kilogram.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.88, p.31

Kan

a unit of cultured pearl weight equal to 1,000 momme (5.122) or 3.75 kilograms.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.103, p.32

Liang

Imperial Chinese unit of weight equal to 250 carats (5.33).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.108, p.33

Methgal

a unit of weight that equals to 4.5 grams.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.120, p.34

Momme

unit of cultured pearl weight, equal to 0.13 ounces or 3.75 grams; 1,000 momme = 1 kan (5.103). This unit was most frequently applied by the Japanese pearl industry to cultured pearls, sometimes spelt monme.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.122, p.34

Once-the-weight

natural pearls are not priced at so much per grain (5.87), but by an elaborate method using base price referred to as the 'unit base price'. By a simple squaring of the weight of an individual pearl in grains and multiplying the result by the base (unit) price the value is arrived at. The pearl trade uses the phrase 'once-the-weight' which is the weight of the pearl squared which is once times its own weight. Often this phrase is abbreviated to 'the once'.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.147, p.40

Sieves

Selections of fine graduated sieves (trays) are used for sorting pearls into different sizes. In the Arabian Gulf these start from Ras (meaning head or biggest pearl) Batin, Theyl, Rubaa, Bukka and finally the Shiteet (meaning seed pearls).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.181, p.43

Weight

mass of a pearl, cultured pearl, diamond, gemstone, synthetic stone or related artificial product. See Clause 5.87, 5.88, and 5.103. NOTE: The SI (Système International) generally uses the term mass instead of weight. Mass is a measure of an object’s inertial property, or the amount of matter it contains. Weight is a measure of the force exerted on an object by gravity or the force needed to support it.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.209, p.46

Necklace lengths

Choker

a strand of uniform sized natural pearls, cultured pearls or imitations of pearls measuring 35-40 cm (14 to 16 inches) in length.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.39, p.25

Collar

a strand of pearls, cultured pearls or imitation pearls measuring 25-33 cm (10 to 13 inches) in length.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.45, p.26

Matinee

a strand of pearls, cultured pearls or imitation pearls measuring 50-60 cm (20 to 24 inches) in length.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.118, p.34

Opera

a strand of natural, cultured or imitation pearls measuring 70-90 cm (28 to 35 inches) in length.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.148, p.40

Princess

a strand of natural, cultured or imitation pearls measuring 43-48cm (17 to 19 inches) in length.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.169, p.42

Rope

a strand of pearls, cultured pearls or imitation pearls measuring about 115cm (45 inches) and longer in length.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.171, p.42

Sautoir

any pearl, cultured pearl or imitation pearl necklace which is longer than opera length necklace 70-90cm (28 to 35 inches). A sautoir is about 90cm (36 inches).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.176, p.43

Appearance and quality descriptors

Body colour

the dominant, overall colour of the natural or cultured pearl.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.26, p.24

Button, or bouton-shaped

a symmetrical domed-shape with or without a flattish bottom.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.32, p.25

Colour

colour has three attributes: hue, tone, and saturation. Hue is the basic impression of colour—yellow, green, blue, etc. Tone is the relative impression of lightness or darkness of the colour. Saturation is the strength or intensity of the colour. In general the colour of nacreous natural and cultured pearls may be described in terms of a combination of ‘body colour’ (5.26), ‘overtone’ (5.153) and ‘orient’ (5.151).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.46, p.26

Lustre

The quality and quantity of light a natural or cultured pearl reflects from its surface or near surface. The appearance is often classified in Europe and the America’s; excellent (reflections are bright, sharp, and distinct), good (reflections are bright but not sharp), fair (reflections are weak, hazy, and blurred) or poor (reflections are dim and diffused).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.110, p.33

Overtone

the presence of an additional or secondary colour on a pearl or pearl product, usually pink, green, or blue.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.153, p.40

Shape

The shapes (or outlines) of a natural and cultured pearl may be broadly divided into five general descriptors; round, near-round, oval, button, drop, and baroque. Natural pearls in Arabian Gulf are classified locally as; “Dana" Perfectly Round (size over 7 mm), "Sijni” or Dam'ah" drop-shaped, "Batan” button shaped, "Baythawi" oval shaped, and "Emtaaz" Baroque.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.180, p.43

Fashioning, drilling and cleaning

Buffing

removing organic residues from the surfaces of natural and cultured pearls following harvest (see also polishing, 5.168).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.31, p.25

Chinese drilling

Two drill-holes that penetrate a pearl or cultured pearl from two different points on the same side, in general the flat or less round side, and meet at a point within the pearl. This drilling was designed to facilitate the use of pearls as buttons.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.37, p.25

Cleaned

a natural or cultured pearl that has had loose extraneous material removed from the surface by employing only water and sometimes mild detergents and /or soft powders.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.42, p.26

Cleaning

following its removal from a mollusc, a pearl maybe cleaned of debris by immersion in water that contains various detergents. This process does not include any bleaching chemicals and is known as ‘cleaning’.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.43, p.26

Drilled

a pearl with a cylindrical hole engineered to enter at one point and exit on the opposite side. Also see part-drilled (5.155) and Chinese drilled (5.37).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.64, p.28

Faceting

a polishing technique applied to natural or cultured pearls, to obtain multiple facets.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.68, p.29

Half-drilled

a pearl with a cylindrical hole engineered to enter at one point but which does not exit. Sometimes known as part-drilled (5.155).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.94, p.31

Part-drilled

a pearl with a cylindrical hole engineered to enter at one point but which does not exit. Sometimes known as half-drilled (5.94).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.155, p.41

Pearl polishing

the action of producing a polish; a technique applied to pearls and cultured pearls to remove some surface blemishes and increase lustre (5.168).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.159, p.41

Polishing

the action of producing a polish; a technique applied to natural and cultured pearls to remove some surface blemishes and increase lustre (also see clause 5.159).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.168, p.42

Trade roles and places

Kharag

the Arabic name given for the person who is a specialist in working (5.210) pearls.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.104, p.32

Pearl Doctor

pearl specialist who can predict which layers to remove from a pearl with a dull and blemished surface to reveal an inner pearl which in most cases could be of a higher lustre and of more value. See clause 5.151.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.157, p.41

Tawash

an Arabian name given to the pearl merchant.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.198, p.45

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)

The 83 pearl-producing molluscs of CIBJO Pearl Book Annex D, with their common names and regional names, are described on a separate page: Pearl-producing molluscs (CIBJO Annex D)

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: §6.2.8, §6.2.9, §6.2.11, §6.2.13, §6.2.15, §6.2.16, §6.2.17, §6.2.18, §6.2.19, §6.2.20, §6.2.21, §6.2.22, the unnumbered table after §6.2.22 (p.61), §6.2.23, §6.2.24, §6.2.25.

How far testing can go

Pearl — what the CIBJO laboratory protocol says to watch for: natural versus non-beaded cultured, possible similarity to other nacreous pearls, blister versus cyst, dye, bleaching, coatings, Maeshori treatment, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada maxima
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other yellowish to brown porcellaneous pearls, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pleuroploca species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other purplish or even white non- nacreous pearls, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Mercenaria mercenaria (quahog)
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other white to lightly coloured non- nacreous/porcellaneous pearls, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from scallops (Pectinidae)
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: blister versus cyst, damage by acids

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from abalone (Haliotis)
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other nacreous pearls, blister versus cyst, dye, bleaching (“Chocolate pearls”), coatings, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada mazatlantica
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other dark hued or purplish nacreous pearls, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Mytilus species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other nacreous pearls, blister versus cyst, dye, bleaching (“Chocolate pearls”), coatings, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada margaritifera
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other white to lightly coloured porcellaneous pearls, shell imitations, CITES, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Tridacna (giant clam) species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity with Melo pearls and other orange porcellaneous pearls, damage by acids, shell imitations.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Cassis species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: natural versus non-beaded cultured, a-typical bead nuclei, possible similarity to other nacreous pearls, blister versus cyst, bleaching, dyes, coatings, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pteria species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: natural versus non-beaded cultured, blister versus cyst, bleaching, irradiation, dyes, Maeshori treatment, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Hyriopsis cumingii and other freshwater mussels
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other brownish or near-white porcelaneous pearls, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Lambis species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: natural versus non-beaded cultured, possible similarity to other nacreous pearls, blister versus cyst, dye, bleaching, coatings, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada radiata
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other dark hued nacreous and non-nacreous pearls, durability of heavily cracked samples, damage by.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinna species (including Atrina)
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

Pearl — what the CIBJO laboratory protocol says to watch for: possible similarity to other nacreous pearls, blister versus cyst, coatings, irradiated bead nuclei in bead cultured pearls, damage by acids.

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada fucata
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

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

Applies only to: pearls from Pinctada maxima; 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: Off-white (stronger than light tones) samples only;
LA-ICP-MS Chemistry: If EDXRF is inconclusive;
X-Ray CT scan: Difficult cases

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada maxima
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

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

Applies only to: pearls from Pteria species; CIBJO laboratory protocol, in its own order; only the notes registered on this site
Test methodWhat the protocol notes for it
PL spectroscopy: Helps with mollusc identification in some cases

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pteria species
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

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

Applies only to: pearls from Hyriopsis cumingii and other freshwater mussels; 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: Off-white (stronger than light tones) samples only;
LA-ICP-MS Chemistry: If EDXRF is inconclusive;
X-Ray CT scan: Difficult cases

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Hyriopsis cumingii and other freshwater mussels
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

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

Applies only to: pearls from Pinctada radiata; 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: Off-white (stronger than light tones) samples only;
X-Ray CT scan: Difficult cases

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada radiata
Source & check 2026-09-26
Source
Fact checked on
2026-09-26

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

Applies only to: pearls from Pinctada fucata; 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: Off-white pearls only

CIBJO Gemmological Laboratories Book 2024

Treatment state
any treatment state
Applies only to
pearls from Pinctada fucata
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

The entry name for Pearl in CIBJO Gemmological Laboratories Book 2024 is Pearl; the Pearl clause of CIBJO Gemmological Laboratories Book 2024 gives a direct definition, and the CIBJO wording is quoted in full under Clause-level definitions on this page. The cross-check result is that it is defined directly by CIBJO and also appears in the GB/T annex.

This table scrolls sideways on narrow screens.

TermClauseDefinitionCross-check
Pearl7.2.2.9natural pearl formations secreted in the interior of molluscs and within naturally formed pearl sacs. They are composed of a complex scleroprotein named conchiolin and of calcium carbonate in the form of aragonite and/or calcite arranged in concentric layers. See the CIBJO Pearl Book for all terms, definitions and classification categories related to pearls. Distinction criteriaDefined directly by CIBJO; also present in the GB/T annex.

Evidence and sources

Authority basis and clause sources

GB/T 16552—2017
Listed Table A.3 “Cultured Pearl(Pearl)” · Source
GB/T 16552—2017
Naming rule 5.1.2.3 b) · Source
CIBJO Gemmological Laboratories Book 2024
Listed §7.2.2.9 “Pearl” · Source
CIBJO Pearl Book 2024
Naming rule 4.4.1.1.2 · Source
16 CFR Part 23
Naming rule §23.20(a) · Source
16 CFR Part 23
Naming rule §23.19(a) · Source
16 CFR Part 23
Naming rule §23.20(b) · Source

Sources

Further reading

Related pages

Treatments recorded for this material

Recorded cultural contexts

Birthstone list

The U.S. Jewelers of America roster lists Pearl for June; the U.K. National Association of Jewellers chart lists Pearl as traditional for June; and Japan's JJA 2021 revised roster lists Pearl for June. 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, June row: Pearl
Japan Jewellery AssociationJapanfrom 20 December 2021Tanjoseki (Japanese birthstone roster, Japan Jewellery Association page; revision of 20 December 2021)
2021 revised birthstone roster, June row: Pearl
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, June row: Pearl (Traditional)

Related intention themes

These reviewed links connect this material with LumaLark intention themes. Each label identifies whether the link is a brand interpretation or a historical and cultural record; neither describes an effect or outcome of the material.

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 (Pearl) is marked.

This table scrolls sideways on narrow screens.

PageContentStatus
Browsing familyPearl and molluscan shell materialsLive
Treatments recorded for this materialBleached, Coated, Dyed (via parent material), Irradiated (via parent material)Live
Related articlesTo be added (placeholder)Planned

Who maintains this page

The material facts in the 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; 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
June
Reviewer
Ralph
How facts are checked
Each fact is matched to the clause it cites; facts checked between 2026-09-17 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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