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Peals Terms and General Definitions

Peals Terms and General Definitions

For the purposes of these CIBJO Standard/rules, the following terms and definitions apply;

5.1. Abalone Cultured Blister
a cultured blister (5.49) from an abalone.(6.1) (Wentzel, 1998, Brown, 1994, Fankboner, 2001, Fankboner, 2002, Liu, 2002, Wentzel, 2004).

5.2. Abalone Pearl
a natural pearl, usually coloured, found in gastropod molluscs of the Haliotis (6.24) genus in the Pacific, Atlantic and Indian Ocean (Kelly, 2003).

5.3. Adductor muscle
the muscle attached to both valves of a bi-valve (5.16) that causes the shell to close when it contracts (Mikkelsen, 2003).

5.4. Akoya
see (6.45 and 6.3) (Mikkelsen, 2003).

5.5. Akoya cultured pearl
a beaded cultured pearl (5.15) produced in Pinctada fucata (martensii) (6.45), the Akoya pearl oyster.

5.6. Artificial products
Products which are composites or imitations (5.84).

5.7. Assembled
See composite (5.42) cultured pearl and assembled cultured pearl blister (5.7).

5.8. Assembled cultured blister
assemblages of a purpose-grown cultured blisters (5.49) which have been cut from their shell, the original bead (5.124) upon which they grew being removed and the cavity filled with various types of man-made materials, and backed by a layer of shell, the assemblages being held together by an adhesive; commonly known as Mabe (5.97) or Hankei (5.79) and occur in both fresh and saltwater environments. Not to be confused with cut cultured pearl (5.50). (Mikkelsen, 2003, Walker, 2001).

5.9. Arabian Gulf
An area in Southwest Asia that is an extension of the Indian Ocean located between Iran and the Arabian Peninsula.

5.10. Arabian Gulf pearls
natural pearls (5.118) produced from the Pinctada Radiata (6.52).

5.11. Bahraini pearl
a natural pearl (5.118) from Bahraini waters in the Arabian gulf produced from the Pinctada Radiata (6.52).

5.12. Baroque
an irregularly shaped natural (5.118) or cultured pearl (5.48). Baroque was originally a French adjective used to describe objects or pearls that were not symmetrical in shape. (Mikkelsen, 2003).

5.13. Basra Pearl
a natural pearl (5.118) from the Arabian gulf produced from the Pinctada Radiata (6.52).

5.14. Bead for cultured pearls
a sphere (usually) or other shape (occasionally) originally formed by cutting and polishing a nacreous shell used to accommodate the nacre (5.110) secreted from a cultured pearl sac (5.47). The bead eventually forms the centre of a beaded cultured pearl (5.15).
Note: Atypically, beads formed from natural (5.118) or cultured pearls (5.48) 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‖.

5.15. Beaded Nacreous Cultured Pearl
beaded cultured pearls are usually nacreous (5.111) formations secreted in the interior of a pearl oyster (5.137). A bead (5.14) is inserted into the mollusc along with a piece of mantle tissue which eventually forms the cultured pearl sac (5.47) around the bead (5.14) 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 (5.44) and of calcium carbonate (usually in the form of aragonite). See nacreous cultured pearls (5.48).

5.16. Bivalve
a member of the molluscan class Bivalvia, having a two-part shell, e.g., clam, oyster, mussel, and scallop (Mikkelsen, 2003).

5.17. Biwa Cultured Pearl
a freshwater beaded or non-beaded cultured pearl produced in Lake Biwa, Japan, using the freshwater bivalve mollusc Hyriopsis schlegeli (6.27). See also 5.179 (Mikkelsen, 2003).

5.18. Black Cultured Pearl
natural colour, cultured black pearl produced using either Pinctada margaritifera (6.49) (the Tahitian cultured pearl (5.171), Pinctada mazatlanica (6.51) or Pteria sterna (6.59) or other pearl oysters (5.137). The colour is not caused by any subsequent processing.

5.19. Black Natural Pearl
natural colour, natural black pearl produced by Pinctada margaritifera (6.49) Pinctada mazatlanica (6.51) or Pteria sterna (6.59). Colour not caused by any subsequent processing.

5.20. Bleaching
to remove, lighten (make whiter) or alter (e.g., from black to brown/bronze) colour by means of chemical and/or physical agents or light. (Shouguo, 2001, Sanchez, 2004).

5.21. Blister cultured pearl
a cultured pearl, (5.48) that has perforated the mantle 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 (5.185).

5.22. Blister natural pearl
a natural pearl (5.118) 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 (Scarratt 2001). Blister pearls are known in the Arabian Gulf as “Nimro”. The base of natural blister pearls may be worked (5.185).

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

5.24. Bombay Bunches
strands of round salt water natural seed pearls (ranging from less than 1 mm to 3 mm)(5.159), 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.

5.25. Bombay pearls
commercial name for natural pearls chiefly from Pinctada radiata (6.52), fished from the Arabian Gulf and Red Sea and exported through Bombay, India (Mikkelsen, 2003).

5.26. Bonding
the union or cohesion brought about by the use of a substance or an agent that causes two or more objects or parts to cohere.

5.27. Bonus cultured pearl
See Lagniappe cultured pearl (5.93) and Keshi cultured pearl (5.91).

5.28. Buffing
removing organic residues from the surfaces of natural and cultured pearls following harvest (see also polishing, 5.148).

5.29. Button-shaped pearl
a symmetrical domed-shape pearl with or without a flattish bottom.

5.30. Carat
unit of weight (5.184) (mass 5.102), equal to one fifth of a gram (200 milligrams) or 4 grains (5.73).

5.31. Cerclé
see circled cultured pearl (5.35).

5.32. Chaw
The chaw is a system of converting weight into volume. Pearls in the Arabian Gulf and India are often sold by chaw. Chaw is calculated as follows:
Chaw = (carat weight)² x 88 / no. of Pearls135
The Chaw price depends on the grade and type of pearls.

5.33. Chinese drilling
a term applied to natural pearls that are, in general, button-shaped and drilled (5.55) with two drill-holes. Both drill-holes penetrate the pearl from different points on the flat or less-round side and meet at a point within the pearl. The drilling was originally designed to facilitate pearls being used as buttons.

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

5.35. Circled cultured pearl
a cultured pearl (5.48) also known as cerclé,(5.31) with one or more concentric rings or indented grooves around it (Mikkelsen, 2003).

5.36. Clam pearl
natural pearl from the hard-shell and giant clams, e.g., Mercenaria mercenaria (quahog)(6.41), Tridacna gigas (giant clam) (6.69) et.al., (Shirai, 1994, Hill., 2004, 1977, Hardy, 1947).
Note: see Clause 2 Normative References; Convention on International Trade in Endangered Species of Wild Fauna and Flora

5.37. 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‘.

5.38. Coating
an artificial layer of any natural or artificial substance spread over the surface, or part of the surface, of pearls for protection, colouration, increased lustre and other optical
phenomena (orient and overtone), decoration or to change appearance; a covering layer.
Note: any natural or cultured pearl (5.118 and 5.48) that is coated, i.e., the outer layer is not composed of nacre laid down by a mollusc, shall be considered an imitation of a pearl (5.84).

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

5.40. 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‘ (5.23), ‗overtone‘ (5.132) and ‗orient‘ (5.130).
Nacreous natural pearls from the Arabian Gulf pearls have a wide selection of colours that have other traditional and distinctive trade names; white (Abyadh), dull white (Basali), black (Aswad), cream with a reddish hue (Nabati), white with a pinkish hue (Mushayer), whitish-blue or whitish-grey (Singbassi), white or cream with a bluish hue (Samawi), white with strong iridescent colours (Gallabi), white or cream with a strong green hue (Akhthar), glassy white or whitish-blue with high lustre (Alzujaji), rose pink (Wardi), light yellow (Ashgar), cream (Keremi).

5.41. Commercial Name
a name assigned for marketing purposes.

5.42. Composite pearl or cultured pearl
Artificial product composed of two or more parts of which at least one is a natural pearl (5.118) or a cultured pearl ( 5.48) ,they may be assembled by bonding ( 5.26) or other artificial methods.

5.43. Conch Pearl
a non-nacreous natural pearl consisting of calcium carbonate arranged concentrically in a crossed lamellar microarchitecture. This structural characteristic usually produces a flame-like surface pattern and porcelaneous sheen. Such pearls are produced by various gastropods including the Queen Conch (Strombus gigas) (6.67), Horse Conch (Pleuroploca gigantea) (6.54), and the Emperor Helmet (Cassis madagasgerensis) (6.8). Also known as pink pearls. See also (6.11) conch. (Farn, 1977, Farn, 1979a, Fritsch, 1987, Moses, 2001, Rutland, 1971, Kornitzer, 1937, Sciaguato, 2004).
Note: see Clause 2 Normative References; Convention on International Trade in Endangered Species of Wild Fauna and Flora

5.44. Conchiolin
protein material (C32H48N2O11) constituting the organic portion of nacre (Mikkelsen, 2003).

5.45. Coque de perle
a shell section, cut from the curved nacreous surface of a polished Chambered nautilus (6.10), then finished like an assembled pearl. Coques de perles are often assembled into jewellery, to resemble large oval half-pearls (Farn, 1979b, Webster, 1966).

5.46. Culture
the growth of biological material, microorganisms, animal tissue or pearls with human intervention, in specially controlled conditions.

5.47. Cultured Pearl Sac
a pearl sac produced / grown from a graft (5.71) of mantle tissue (5.99) artificially inserted into the body of a host mollusc or created from mantle damage due to human handling.

5.48. Cultured Pearls
See 5.114, and 5.121

5.49. Cultured Blister
See 5.115

5.50. Cut Cultured Pearls
cultured pearls (5.48) that have been cut in half or three quarters to produce a flat base.

5.51. Cut Natural Pearls
natural pearls (5.118) that have been cut to produce a flat base.

5.52. Cyst pearls
natural pearls (5.118) that occur in a pearl-sac (5.139) and not in direct contact with the shell of a pearl-producing mollusc.

5.53. Dobo pearls
a commercial name for cultured pearls traded and exported through Dobo in Indonesia.

5.54. Dyeing
application of a dye or stain to natural materials or artificial products.

5.55. Drilled
a pearl with a cylindrical hole engineered to enter at one point and exit on the opposite side. Also see part-drilled (5.134) and Chinese drilled (5.33).

5.56. Essence d‟orient
French term for a solution of powdered fish scales in resin or other coating, used for manufacturing imitation pearls (5.84) (Mikkelsen, 2003).

5.57. Faceted cultured pearls
cultured pearls (5.48) with multiple flat, convex or concave facets that have been artificially formed on their surface (Hurwit, 2001).

5.58. Faceting
a polishing technique applied to cultured pearls (5.48), to obtain multiple facets.

5.59. Filling
to introduce a substance that occupies a whole or part of a void in a pearl.

5.60. Fine pearl
see natural pearl (5.118).

5.61. Fissure
a very narrow opening; a fine fracture.

5.62. Fracture filling
To occupy the whole or part of a fracture with a substance, e.g. glass, resins, oil, etc.; to pervade; to spread throughout; to occupy completely; or make full, with the purpose of making the fracture less visible.

5.63. Frequency
the rate of occurrence (according to current knowledge) for a treatment being applied to pearls including bleaching, bonding, dyeing, irradiating, oiling, staining, tinting and/or waxing. Expressed as None: Unknown: Rarely: Uncommon: Occasionally: Common: Usually: or Always: in Annex A.

5.64. Freshwater
a body of water that is non-saline, e.g., rivers, lakes, ponds and marshes.

5.65. Freshwater Cultured Pearl
cultured pearls (5.48) produced in molluscs (mussels) in freshwater, e.g., Hyriopsis schlegelii (6.27), Hyriopsis cumingii (6.26). (Mikkelsen, 2003, Sweeny, 1982, Jobbins, 1993, Hänni, 2000, Scarratt, 2000, Akamatsu, 2001).

5.66. Freshwater Natural Pearl
A natural pearl (5.118) produced by a bi-valve (5.16) mollusc (5.107) living in freshwater (5.64).

5.67. Genuine
actually possessing the alleged or apparent attribute or character.

5.68. Gonad
the sex or reproductive organ.

5.69. Gonad grown cultured pearl
a cultured pearl (5.48) grown in the gonad (5.68) of a pearl producing mollusc.

5.70. Gonad natural pearl
a horn or cusp-shaped natural pearl common in abalone (6.1), formed in the similarly shaped reproductive organ or gonad (5.68).

5.71. Graft
a piece of epithelium tissue cut from the mantle (5.99) of a nacre (5.110) -producing mollusc that is inserted into the body of another nacre producing mollusc (5.107), (usually of the same species), to initiate the growth of a cultured pearl sac (5.47) and a cultured pearl (5.48).

5.72. Grafting
the action of introducing tissue cut from the mantle (5.99) of a nacre (5.110) -producing mollusc into the body of another nacre-producing mollusc (5.107) (usually of the same species) to initiate the growth of a cultured pearl sac (5.47) and a cultured pearl (5.48). Grafting can be done into the recipient oyster‘s mantle (5.99 ) or gonad (5.68) – mantle-grown cultured pearls (5.100) or gonad-grown cultured pearls (5.69).

5.73. Grain
0.25 of one carat (ct) (0.25ct, equivalent to 0.05 gram or 50 milligrams).

5.74. Gram
1/1000 of a kilogram.

5.75. Gulf pearl
a natural pearl (5.118) from the Arabian Gulf produced from the Pinctada Radiata.

5.76. Half composite cultured pearl
see 5.42

5.77. Half cultured blister
see 5.49.

5.78. Half cultured pearl
see 5.50.

5.79. Hankei
Japanese trade term for cultured blister (5.49).

5.80. Heating
to heat a pearl or cultured pearl to a temperature that alters its appearance. (Elen, 2001, Elen, 2002, Elen, 2003).

5.81. Hinge pearl
a natural pearl of irregular and usually elongated shape, found near the hinge of bi-valve (5.16) molluscs – not cut from the shell (Du Toit, 1997).

5.82. Hollow cultured pearl
a cultured pearl (5.48) with a large enclosed cavity.

5.83. Hollow pearl
a natural pearl (5.118) with a large enclosed cavity.

5.84. Imitation Pearls
products that simulate the appearance of natural (5.118) or cultured pearls (5.48) without possessing their chemical composition and/or their physical properties and/or their structure. Any product which is pearl-like in appearance is an imitation pearl if its outer layers are not completely composed of a natural substance secreted in the interior of the productive molluscs (see Simulated 5.162).

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

5.86. Irradiating
to expose to or process with radiation.

5.87. Irradiation
exposing natural or cultured pearls to radiation to alter their appearance.

5.88. Kan
a unit of pearl weight equal to 1,000 momme (5.108) or 3.75 kilograms.

5.89. Kharag
the Arabic name given for the person who specialists in working pearls.

5.90. Keshi
an old but misused Japanese trade term meaning a small natural seed pearl (5.118 and 5.159). See Keshi Cultured Pearl (5.91).
Note: the term Keshi used without qualification has been misused and is not recommended terminology for any type of pearl product unless qualified with either ‗natural‘ or ‗cultured‘, whichever is appropriate.

5.91. Keshi Cultured Pearl
a trade term that designates a non-beaded cultured pearl (5.120) formed accidentally or intentionally by human intervention in marine pearl oysters such as the Akoya oyster (Pinctada fucata 6.45), Silver/Gold lipped oyster (6.66) (Pinctada maxima 6.50) and Black lipped oyster (Pinctada margaritifera 6.49) and is a by-product of the culturing process. The creation results from the formation of a pearl sac either following injury of the mantle rim upon human handling, from a partial piece of the inserted (grafted) mantle tissue (5.99) or the whole inserted piece (5.142) following the rejection of a bead (5.14). See also South Sea Keshi Cultured Pearl (5.166). (Hänni, 2006). Alternative name; Lagniappe (or Bonus) Cultured Pearl (5.93).

5.92. Kilogram
the kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.

5.93. Lagniappe cultured pearls
cultured pearls that are a by-product of the culturing process in the USA, the term, is said to be derived from the New World Spanish la ñapa, “the gift,” and ultimately from Quechua yapay, “to give more.” The word came into the rich Creole dialect mixture of New Orleans and there acquired a French spelling. It is still used in the Gulf States of the USA, especially southern Louisiana, to denote a little bonus. By extension, it may mean “an extra or unexpected gift or benefit. See also Keshi cultured pearl (5.91).

5.94. Liang
Imperial Chinese unit of weight equal to 250 carats (5.30).

5.95. 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).
In the Arabian Gulf the lustre of natural pearls is classified as; Jiwan “meaning beauty in India (excellent perfect lustre), Shireen “meaning sweet in India” (very good lustre), Gholwah “meaning round Pearls” (Average lustre), and Badlah “meaning irregular pearls” (Poor to average lustre).

5.96. Lustre enhancement
any treatment or process applied to enhance the lustre of a natural or cultured pearl, e.g., “maeshori‖ (5.98)

5.97. Mabe
Japanese trade term designating an assembled cultured blister (5.8) from Pteria penguin (6.58) the Mabe oyster (6.32), (Scarratt, 1992).

5.98. Maeshori treatment
a multi-part chemical treatment that temporarily enhances lustre.

5.99. 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.

5.100. Mantle grown cultured pearl
a cultured pearl (5.48) grown in the mantle (5.99) of a producing mollusc.

5.101. Marine Gastropod
a univalve mollusc that lives in the sea, e.g., (5.43) and (5.104).

5.102. Mass
see weight (5.184), and (5.73, 5.74, 5.88, and 5.108). The SI (Système International) generally uses the term mass (5.102) instead of weight (5.184). 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.

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

5.104. Melo Pearl
a natural non nacreous pearl (5.122) found in one of the melo volutes (6.36, 6.37, 6.38, 6.39 and 6.40) (Sciaguato, 2004, Traub, 1999, Traub, 1997).

5.105. Methgal
a unit of weight that equals to 4.5 grams.

5.106. Modification
See Treatment 5.182.

5.107. Mollusc
an invertebrate (5.85) animal of the phylum Mollusca.

5.108. Momme
unit of pearl weight, equal to 0.75 ounces or 3.75 grams; 1,000 momme = 1 kan (5.88). This unit was most frequently applied by the Japanese pearl industry to cultured pearls, sometimes spelt monme.

5.109. Mother-of-pearl
the smooth, hard, iridescent coating on the inner surface of some species of molluscs, composed of microscopic crystals of aragonite and/or calcite (a form of calcium carbonate) deposited in thin layers with organic conchiolin; scientifically known as nacre (5.110). Usually pearls produced by the particular mollusc have the same colour composition and general quality as the mother-of-pearl of the particular mollusc.

5.110. Nacre
biogenic material of nacreous natural (5.116) and cultured (5.46) pearls. Nacre is composed of layers of microscopic platelets of aragonite and/or calcite (calcium carbonate), bound together by a fine network of a complex scleroprotein called conchiolin (5.44). This characteristic structure produces optical effects (orient, overtone) from within the pearl. Nacre is secreted from the mantle (5.99) of pearl oysters (5.137) and some gastropods.

5.111. Nacre thickness
the thickness of nacre (5.110) overlaying the nacreous shell bead (5.14) in a beaded cultured pearl, usually expressed as an average in millimetres. Nacre thickness is only relevant in the case of beaded cultured pearls (5.15). It refers strictly to the thickness of the nacre covering the nacreous shell 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 (5.15).

5.112. Nacre volume
expressed as a percentage of the total volume of a bead cultured pearl when excluding the bead.

5.113. Nacreous
composed of nacre (5.110).
pearls produced with or without the insertion by man of a bead (5.14) initially by grafting (5.72) mantle tissue that eventually forms a cultured pearl sac (5.47), 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 (5.47) 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 (5.111), unattached formations, secreted within a cultured pearl sac (5.47) in the interior of pearl oysters (5.137) including Pinctada maxima (6.50), Pinctada margaritifera (6.49), Pinctada mazatlanica (6.51), Pinctada fucata (6.45), Pteria penguin (6.58), and Pteria sterna (6.59) as well as the freshwater mussels Cristeria plicata (6.12), Hyriopsis schlegeli (6.27) and Hyriopisis cumingii (6.26).
The surfaces of nacreous cultured pearls are composed of nacre (5.110) that is laid down in concentric layers while within the cultured pearl sac (5.47). The secretion of the nacreous layers from the cultured pearl sac (5.47), within of the pearl oyster (5.137) is a natural process instigated and partially controlled by man. This applies to all cultured pearls whether grown with or without a bead (5.14). The term ‗cultured‘ is applied to pearls that have been cultured (5.46) and is not applied to other pearls.

5.114. Nacreous Cultured Pearls
pearls produced with or without the insertion by man of a bead (5.14) initially by grafting (5.72) mantle tissue that eventually forms a cultured pearl sac (5.47), 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 (5.47) 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 (5.111), unattached formations, secreted within a cultured pearl sac (5.47) in the interior of pearl oysters (5.137) including Pinctada maxima (6.50), Pinctada margaritifera (6.49), Pinctada mazatlanica (6.51), Pinctada fucata (6.45), Pteria penguin (6.58), and Pteria sterna (6.59) as well as the freshwater mussels Cristeria plicata (6.12), Hyriopsis schlegeli (6.27) and Hyriopisis cumingii (6.26).
The surfaces of nacreous cultured pearls are composed of nacre (5.110) that is laid down in concentric layers while within the cultured pearl sac (5.47). The secretion of the nacreous layers from the cultured pearl sac (5.47), within of the pearl oyster (5.137) is a natural process instigated and partially controlled by man. This applies to all cultured pearls whether grown with or without a bead (5.14). The term ‗cultured‘ is applied to pearls that have been cultured (5.46) and is not applied to other pearls.

5.115. Nacreous Cultured Blister
a nacreous cultured blister attached to the shell of a mollusc. A cultured blister is formed following the insertion by man of a nacreous or non-nacreous material that is or becomes attached to or lies against the inside of the shell of a mollusc. The mantle tissue (5.99) secretes layers of nacre on the material‘s surface. These nacreous layers form over the inserted material and continue onto the interior of the shell, making one cohesive whole between the shell, the material and the newly formed nacreous layers. Following harvest, the cultured blister is cut from the shell, the material remaining in position.

5.116. Natural
substances which have been formed completely by nature without human interference and subsequently modified, if at all, only by means set out in (4.8.2.1).

5.117. Natural Blisters
a blister, is an internal protuberance of the shell caused by the intrusion of foreign bodies between the mantle and the shell The interior may or may not be hollow and the secretion occurs naturally, without human intervention.

5.118. Natural Pearls
natural pearl formations secreted, without human intervention, in the interior of molluscs and within naturally formed pearl sacs (5.139). They are composed of a complex scleroprotein named conchiolin (5.44) and of calcium carbonate in the form of aragonite and or calcite arranged in concentric layers. Natural pearls may be nacreous (5.111) or non-nacreous. (5.122). See also 5.13 and 5.11.

5.119. Natural Pearl Sac
see Pearl Sac (5.139)

5.120. Non-beaded cultured pearl
a cultured pearl (5.48) grown without a bead (5.14).

5.121. Non-Nacreous Cultured Pearls
pearls produced with or without the insertion by man of a bead (5.14) by grafting (5.72), mantle tissue that eventually forms a cultured pearl sac (5.47), 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 (5.47) 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 (5.47) in the interior of Strombus gigas (6.67) and are referred to as cultured conch pearls (5.43), 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 (5.14). The term ‗cultured‘ is applied to pearls that have been cultured (5.46) 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

5.122. Non-nacreous natural pearls
natural pearls without a nacreous surface layer, e.g., clam pearls (5.36), conch pearls (5.43), melo pearls (5.104), some pen pearls (5.141) and scallop pearls (5.157).
Note: see Clause 2 Normative References; Convention on International Trade in Endangered Species of Wild Fauna and Flora

5.123. Non-nucleated cultured pearl
a term used in the trade for a non-beaded (5.120) and keshi (5.91) cultured pearls.

5.124. Nucleus
a bead (5.14) around which a beaded cultured pearl (5.15) is formed.

5.125. Objet d‟art
an object considered to be of artistic worth.

5.126. Oiling
a process, called ‗decraqueler‘, sometimes applied to natural and cultured pearls, whereby the surface of pearls are soaked in warm oil; to diminish the appearance of cracks.

5.127. Once-the-weight
natural pearls are not priced at so much per grain (5.73) 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’.

5.128. Opera
a strand of pearls measuring 70-90cm (28 to 35 inches) in length.

5.129. Organic substances
natural products of animal or plant origin used in jewellery or objets d’art.

5.130. 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 colours.

5.131. Oriental Pearl
an old commercial name for some natural saltwater pearls (5.118).

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

5.133. Oyster
a common name applied to a number of bi-valved molluscs (5.16) (Kai in Japanese), some of them not closely related. Pearl oysters are of the family Pteriidae. True (edible) oysters are of the family Ostreidae. Tree oysters are of the family Isognomonidae.

5.134. Part-Drilled
a pearl with a cylindrical hole engineered to enter at one point but which does not exit. Sometimes known as half-drilled.

5.135. Pearl
See natural pearl 5.118.

5.136. 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.

5.137. Pearl Oyster
marine bivalves classified in the family Pteriidae and the genera Pinctada and Pteria, e.g., Pinctada maxima (6.50), Pinctada margaritifera (6.49), Pinctada mazatlanica (6.51), Pinctada fucata (martensii) (6.45 and 6.48), Pinctada imbricata (6.46), Pinctada radiata (6.52), Pinctada maculata (6.47) ,Pteria penguin (6.58), and Pteria sterna (6.59).

5.138. Pearl Polishing
the action of producing a polish; a technique applied to pearls and cultured pearls to remove some surface blemishes and increase lustre (5.148).

5.139. Pearl-sac
a pearl-sac is naturally derived from the internal or external layer of the epithelium of the mantle (5.99) or of the gill plates. The epithelial cells of the pearl-sac secretes mainly nacre (5.110) in the case of pearl-oysters (5.137) 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 (5.47).

5.140. Peeling
a technique applied to lightly remove layers of nacre (5.110) from a pearl. Also see working (5.185).

5.141. Pen Pearl
see Pinna Pearl (5.146).

5.142. Piece
a ―piece‖ of mantle tissue (5.99).

5.143. Piece holder
tool to catch the graft (5.71) or mantle tissue (5.99) piece (5.142) for insertion during the grafting (5.72) procedure; also known as piece needle (5.144).

5.144. Piece needle
see piece holder (5.143).

5.145. Piece process
a ―piece‖ of mantle tissue from a donor mollusc is grafted, by man, into a host mollusc to begin the formation of a cultured pearl sac (5.47), the essential part of the culturing process (termed the ―piece process‖).

5.146. Pinna pearl
a natural orange non-nacreous or silvery ‗nacreous‘ pearl, produced by a pen shell (also see pen pearl 5.141), a marine bivalve mollusc of the genus Pinna or Atrina (family Pinnidae) (Wentzel, 2005).

5.147. Point of Sale
the point in time when items for sale are sold and payment terms are agreed upon.

5.148. 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 5.138).

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

5.150. Processed
a natural (5.118) or cultured pearl (5.48) that has been drilled ( 5.55 and 5.33 ), cut (5.50 and 5.51), polished (5.138), buffed (5.28) , peeled (5.140), worked (5.185) or cleaned (5.37).

5.151. Real
genuine (5.67); not artificial. (See clause 4.10.4).

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

5.153. Saltwater
a body of water that is saline e.g., sea, oceans, lagoons.

5.154. Saltwater Cultured pearl
a cultured pearl produced by a saltwater mollusc (5.107).

5.155. Saltwater Natural Pearl
a natural pearl (5.118) produced by a saltwater mollusc (5.107).

5.156. 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).

5.157. Scallop Pearl
a natural pearl produced by one of the scallops (pectinidae) (6.65). They are non-nacreous (5.122) but differ in surface appearance and composition to other non-nacreous pearls such as the conch (5.43) and melo (5.104) 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 (Scarratt, 2004, Wight, 2004, Federman, 2004).

5.158. Scottish pearls
natural freshwater pearls from Margaritifera margaritifera (6.34) in Scotland.

5.159. Seed Pearl
a small salt or freshwater natural pearl (5.118) which is generally less than two millimetres in diameter.

5.160. Shape
The shapes (or outlines) of a natural and cultured pearl may be broadly divided into seven descriptors; round, near-round, oval, button, drop, semi-baroque 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.

5.161. 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)

5.162. Simulant
see (5.84) imitation

5.163. Skinning
see peeling (5.140).

5.164. South Sea
an area of the Pacific and the Indian Oceans (including the Indian Ocean) between Myanmar and Northern Australia and inclusive of Indonesia and the Philippines, the habitat of the Pinctada maxima (6.50) pearl oyster.

5.165. South Sea cultured pearl
a cultured pearl (5.48) from a Pinctada maxima (6.50). Extensively cultured in areas of the Indian and Pacific Oceans, including Myanmar, Indonesia, Philippines, and Northern Australia.

5.166. South Sea Keshi Cultured Pearl
a trade term for a keshi cultured pearl grown in Pinctada maxima (6.50). A South Sea (5.164) keshi cultured pearl (5.91) or a South sea non-beaded cultured pearl formed accidentally in Pinctada maxima, it is a by-product of the culturing process. The creation results from the formation of a cultured pearl-sac (5.47) either following injury of the mantle rim upon handling, or from a partial piece of the inserted (transplanted) mantle tissue (5.99), or the whole inserted piece (5.142) following the rejection of a bead (5.14). Some are hollow or contain relatively large amounts of organic matter (Smith, 2001, Wentzell, 2000).

5.167. Spat
larval molluscs (5.107) that have settled on a hard substratum, to grow to adulthood.

5.168. Special care
additional care needed to preserve the appearance of natural and cultured pearls, or artificial products (4.10.4) or any alteration that may have been applied.

5.169. Stability
a measure of the ability of gemstones and organic substances (5.129) to maintain their appearance under normal wear and care.
the ability of a process or a treatment, including bleaching, bonding, dyeing, irradiating, oiling, staining, tinting and waxing, to retain its appearance in pearls and cultured pearls, under normal wear, repair, cleaning and/or display conditions, and after re-cutting.
NOTE: Some pearls that are not subjected to the processes mentioned above may change in appearance over a period of time.

5.170. Tahiti cultured pearl
see Tahitian cultured pearl (5.171).

5.171. Tahitian cultured pearl
a naturally coloured cultured pearl resulting from grafting and breeding in a natural environment, in French Polynesia, of the pearl oyster Pinctada margaritifera (6.49) var. cumingii. It results from the secretion of nacre by a grafted (5.71) cultured pearl sac (5.47) (piece of epithelium of the mantle (5.99) collected from the donor oyster from French Polynesia) around a bead (5.14) inserted in the gonad of this pearl oyster.

5.172. Tahiti Keshi cultured pearl
a trade term for a keshi cultured pearl grown in Pinctada margaritifera in French Polynesia. The Tahiti keshi cultured pearl (see also 5.91) or Tahiti non-beaded cultured pearl (5.120), is formed accidentally in Pinctada margaritifera in French Polynesia and is a by-product of the culturing process. The creation results from the formation of a cultured pearl sac (5.47) either following injury of the mantle rim upon handling, from a partial piece of the inserted (transplanted) mantle tissue (5.99) or the whole inserted piece (5.142) following the rejection of a bead (5.14). Some Tahiti keshi cultured pearls are hollow or contain relatively large amounts of organic matter.

5.173. Tahiti natural pearl
a natural pearl (5.118) secreted in the interior of the pearl oyster Pinctada margaritifera (6.49) var. cumingii native to French Polynesia.

5.174. Thawash
an Arabian name given to the pearl merchant.

5.175. Three-quarter composite cultured pearl
see 5.42.

5.176. Three quarter cultured blister
see 5.49.

5.177. Three quarter cultured pearl
See 5.50.

5.178. Tinting
a treatment which causes a subtle change in colour and/or appearance.

5.179. Tissue nucleated cultured pearl
a term used in the trade for a non-beaded cultured pearl (5.48).

5.180. Trade codes
a list used within the trade, consisting of one or more letters, for labelling the modification of gemstones and organic substances (5.106) (See Annex A)

5.181. .
a natural or cultured pearl whose appearance has been altered through any action by man other than by polishing (5.148), drilling (5.55 and 5.33), cutting (5.50), buffing (5.28), peeling (5.140), or cleaning (5.37); e.g., by coating (5.38), dyeing (5.54) – including tinting (5.178), irradiation (5.87), filling (5.59) , heating (5.80) oiling (5.126) waxing (5.183) working (5.185) and bleaching (5.20).

5.182. Treatment
any action by man (other than polishing (5.148), cleaning (5.37), buffing (5.28), peeling (5.140), drilling (5.55) and cutting (5.50)) that alters the appearance of a pearl or cultured pearl.

5.183. Waxing
the application of a colourless wax or similar products to, or near, the surface of a pearl.

5.184. Weight
mass (5.102) of a pearl. The SI (Système International) generally uses the term mass (5.102) instead of weight (5.184). 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, see Clause 5.73, 5.74, 5.88, and 5.108.

5.185. Working
a process that removes blemishes or reshapes mainly natural pearls. Often applied to natural blister pearls (5.22) to remove or disguise any remaining shell attachment and to natural pearls that are out-of-round to baroque in order to give them a round shape. Not commonly applied to cultured pearls. See for comparison ‗peeling‘ (5.140).

Articles source: THE PEARL BOOK, Natural, Cultured, Composite & Imitation Pearls — Terminology & Classification (Including information on modifications), 2013-08-12, CIBJO/Pearl Commission.

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