Natural Pearl

Registered material facts

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PropertyFinding (each row expands to source and check date)

Definition

Structure

Durability

Physical properties

Optical

Quality factors

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

Related CIBJO terms

Abalone Pearl

a natural pearl, usually multi-coloured blue or green hue, found in gastropod molluscs of the Haliotis (9.28) genus in the Pacific, Atlantic and Indian Ocean.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.2, p.22

Arabian Gulf

an area in Southwest Asia that is an extension of the Indian Ocean located between Iran and the Arabian Peninsula, sometimes known as the Persian Gulf.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.9, p.22

Arabian Gulf pearls

natural pearls produced from the Pinctada radiata (9.62).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.10, p.23

Bahraini pearl

a natural pearl from Bahraini waters in the Arabian gulf produced from the Pinctada radiata (9.62).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.15, p.23

Basra pearl

a natural pearl from the Arabian gulf produced from the Pinctada radiata (9.62).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.17, p.23

Black natural pearl

natural colour, natural black pearl produced by Pinctada margaritifera cumingii (9.58 Pinctada mazatlanica (9.61) or Pteria sterna (9.69). Colour not caused by any subsequent processing.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.24, p.24

Bombay bunches

strands of round salt water natural seed pearls (ranging from less than 1 mm to 3 mm) (5.179), mostly with medium to high lustre and well-matching colour. These bunches are known by the trade as Bombay Bunches and are mostly marketed in Europe.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.27, p.24

Bombay pearls

commercial name for natural pearls chiefly from Pinctada radiata (9.62), fished from the Arabian Gulf and Red Sea and exported through Bombay, (now known as Mumbai) India.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.28, p.25

Clam pearl

natural pearl from the hard-shell and giant clams, e.g., Mercenaria mercenaria (quahog) (9.48), Tridacna gigas (giant clam) (9.82). 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): §5.41, p.26

Cyst pearls

natural pearls (5.136) that occur in a pearl sac (5.160) and not in direct contact with the shell of a pearl-producing mollusc.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.60, p.28

Gonad natural pearl

a horn or cusp-shaped natural pearl common in abalone (9.1), formed in the similarly shaped reproductive organ or gonad (5.82).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.84, p.30

Gulf pearl

a natural pearl from the Arabian Gulf produced from the Pinctada radiata.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.89, p.31

Hinge pearl

a natural pearl of irregular and usually elongated shape, found near the hinge of bivalve (5.21) molluscs – not cut from the shell. Note - The term hinge pearl has been used in the USA to describe a piece of shell that was carved from the hinge of freshwater molluscs to simulate the look of a natural pearl called the wing or feather pearl which grows in the region of the hinge.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.97, p.31

Hollow pearl

a natural pearl with a large enclosed cavity.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.99, p.32

Lightly worked natural pearl

a natural blister pearl (5.134) that has been lightly worked. (5.210). Figure 1 Examples of lightly worked natural (nacreous) pearls that after “working” reveal the original natural pearl at their heart.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.109, p.33

Mussel pearl

rare cream, purple or black nacreous natural pearl from the marine brown mussel, also known as Philippine horse mussel, Modiolus philippinarum, of the Mythilidae family that is fished as seafood in the Philippines, Mozambique that may reach up to 9 mm in diameter. May also be found in other bivalves from Mytilidae.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.125, p.35

Natural blisters

a nacreous blister, is an internal protuberance of the shell, which may be low or high domed, caused by the intrusion and trapping of foreign bodies between the mantle and the inner surface of the shell that have entered through the live opened shell or have bored through the shell from the exterior. The interior of the blister may or may not contain the remains of a variety of skeletal, plant or mineral forms indeed they are often hollow following the decomposition of an organic intrusion. The secretion occurs naturally, without human intervention. Figure 2: a stylized line-drawing showing two possibilities of how a natural blister is formed on the interior surface of a shell. NOTE: - While in most circumstances it is possible to distinguish between ‘natural (nacreous) blisters’ (5.133), ‘lightly worked natural (nacreous) pearls’ (5.109) and natural (nacreous) blister pearls (5.134), it may at times be technically challenging to make this important distinction. In concluding that the formation is a ‘natural (nacreous) blister’ one should be confident, through whatever means available, that the development began with the natural intrusion, into the area between the shell and the mantle of a pearl oyster, of a foreign material. NOTE: - It is important to remember that natural (nacreous) blisters as described in this definition may be artificially produced by man inserting foreign objects such as shells, fish and carved images between the mantle and the inner layer of the shell. Such products are covered under the various sections that describe the various culturing operations.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.133, p.36

Natural blister pearl

a natural pearl that has perforated the mantle of the mollusc and has naturally 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 are secreted without human intervention. Blister pearls are known in the Arabian Gulf as "Nimro". The base of natural blister pearls may be worked (5.210). Figure 3: a stylized line drawing showing a possible scenario for the formation of a natural pearl that has become adhered to the inner wall of the shell after the natural pearl sac is perforated. Note that the gap between the mantle and the shell as well as other parts are exaggerated for clarity. NOTE: While in most circumstances it is possible to distinguish between a natural (nacreous) blister pearl (5.133), a ‘lightly worked natural (nacreous) pearl’ (5.109) and a ‘natural (nacreous) shell blister’ (5.133) it may at times be technically challenging to make this important distinction. In concluding that the formation is a natural (nacreous) blister pearl (5.133), or a ‘lightly worked natural (nacreous) pearl’ one should be confident, through whatever means available, that the development began within a pearl sac in the mantle of the “pearl oyster” and subsequently the mantle has laid down further layers of nacreous and non-nacreous material on top of the pearl which are continuous with those of the inner wall of the shell (5.109).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.134, p.37

Natural pearls

natural pearl formations secreted, without human intervention, in the interior of molluscs and within naturally formed pearl sacs (5.160). They are composed of a complex scleroprotein named conchiolin (5.49) and of calcium carbonate in the form of aragonite and/or calcite arranged in concentric layers. Natural pearls may be nacreous (5.127) or non-nacreous. (5.141). See also 5.15 and 5.17.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.136, p.38

New World natural pearl

a natural pearl produced by Pinctada mazatlanica (Hanley, 1855), (9.61), also known as the La Paz pearl oyster, or the Panamic Black-Lipped pearl oyster. Fisheries gave abundant supplies of naturally coloured pearls, from light-grey to black, with many intermediate tones of pink, gold and green. Pinctada mazatlanica is used today to produce limited quantities of Mabe bead cultured pearls.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.138, p.38

Non-nacreous natural pearls

natural pearls without a nacreous surface layer, e.g., clam pearls (5.41), conch pearls (5.48), Melo pearls (5.119), some pen pearls (5.162) and scallop pearls (5.177). 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): §5.141, p.39

Oriental pearl

an old commercial name for some natural saltwater pearls (5.136).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.152, p.40

Pearl sac

a pearl sac is naturally derived from the internal or external layer of the epithelium of the mantle (5.111). The epithelial cells of the pearl sac secrete mainly nacre (5.126) in the case of pearl-oysters (5.158) and a non-nacreous calcium carbonate in the form of aragonite or calcite in the case of molluscs other than pearl-oysters, which becomes deposited over the foreign body, forming a natural pearl in due course of time. See also cultured pearl sac (5.54).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.160, p.41

Peeling

a technique applied to remove the outer but loosely adhering layers of nacre (5.126) from a natural pearl to reveal a pristine layer of nacre below. Not to be confused with working (5.210).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.161, p.41

Pinna pearl

a natural orange or brown non-nacreous or nacreous, or silvery ‘nacreous’ pearl, produced by a pen shell (also see pen pearl clause 5.162), a marine bivalve mollusc of the genus Pinna or Atrina (family Pinnidae).

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.167, p.42

Scallop pearl

a natural pearl produced by one of the scallops (Pectinidae) (9.77). They are non-nacreous (5.141) but differ in surface appearance and composition to other non-nacreous pearls such as the conch (5.48) and Melo (5.119) varieties. The surface appearance is comprised of a patchwork of cells with each cell being formed from three sub-cells. The orientation of these sub-cells and the low magnification fibrous appearance of structures within them give the scallop pearl a peculiar surface sheen.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.177, p.43

Seed pearl

a small saltwater or freshwater natural pearl (5.136) which is generally less than two but no more than three millimetres in diameter.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.179, p.43

Tahitian natural pearl

a natural pearl secreted in the interior of the pearl oyster Pinctada margaritifera cumingii (9.58) native to French Polynesia.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.197, p.45

Venezuelan pearl

natural pearl found in Pinctada imbricata (Röding, 1798) or the Atlantic Pearl Oyster, ranges naturally in the western Atlantic from Bermuda and Florida to northern South America. The Atlantic Pearl Oyster is the source of Columbus’s pearls.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.206, p.46

Working

a method used that removes blemishes or reshapes mainly natural pearls. Often applied to natural blister pearls (5.134) that had become attached to the inner wall of the shell to remove or disguise any remaining shell attachment (lightly worked Figure 4) and to natural pearls (5.136) that are out-of-round to baroque in order to give them a round shape (heavily worked Figure 5), most commonly seen with non-nacreous natural pearls. Not commonly applied to cultured pearls. Not to be confused with ‘peeling’ (5.161). it is important that working, whether light or heavy, is stated in any documentation describing a natural or cultured pearl. Figure 4: schematic drawing showing a progression from A where a natural pearl is adhering to the shell, B where the shell has been removed by cutting and grinding and C where the edges have been lightly worked either to fit an item of jewellery or simply to make the pearl more presentable. D are actual examples where the A to C process has taken place. Figure 5: Schematic drawing showing a progression from A where a natural Melo (or any other type on non-nacreous) pearl is baroque and maybe poor on the surface, B showing the areas to be ground away to form a round pearl and C the heavily ‘worked to round’ natural Melo (or any other type on non-nacreous) pearl revealing previously internal growth feature now on the surface and D an actual example.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.210, p.46

Fashioning, drilling and cleaning

Cut natural pearls

natural pearls that have been cut to produce a flat base.

CIBJO Blue Book — Pearl Book (Pearl Commission 2024-1) (CIBJO): §5.59, p.28

Entries in the source that only point to another clause: Fine pearl (§5.71, p.29) → §5.136 Natural pearls; Natural pearl sac (§5.137, p.38) → §5.160 Pearl sac; Pearl (§5.156, p.41) → §5.136 Natural pearls; Pen pearl (§5.162, p.41) → §5.167 Pinna pearl; Skinning (§5.183, p.43) → §5.161 Peeling

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): §9.1 Abalone · §9.28 Haliotis · §9.48 Mercenaria mercenaria · §9.58 Pinctada margaritifera cumingii · §9.61 Pinctada mazatlanica · §9.62 Pinctada radiata · §9.69 Pteria sterna · §9.77 Scallop · §9.82 Tridacna gigas

Authority basis and clause sources

Body / standardStatus · clause or name · original

GB/T 16552—2017

Listed Table A.3 “Natural Pearl” · Source

GB/T 16552—2017

Naming rule 5.1.2.3 a) · 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

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.

Related pages

Treatments recorded for this material

• Bleached
• Dyed

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 (Natural 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