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Glossary of Pearl Terms I

Glossary of Pearl Terms I

I-pearls: Imitation pearls from Izumi, Japan.

icon pearl: Cultured blister pearl produced in the shape of an iconic object by using a nucleus of that shape.

IGI grading system: Cultured pearl grading system developed by the International Gemological Institute in New York in 1993. The system uses 22 reference strands to grade color, luster, nacre, shape and surface according to point values ranging from 1 (lowest) to 30 (highest).

ikecho-gai: Japanese name for the Biwa pearly mussel, Hyriosis schlegeli. Translated to English, ikecho-gai is pond butterfly shell.

image pearl: An image pearl, similar to an icon pearl, is a cultured blister pearl in the shape of an image like a Buddha or a dragon; first cultured in Cristaria plicata (cockscomb) mussels in China in the late 1200s.

imitation pearl: Any material that simulates the appearance of a cultured or natural pearl but does not possess either?s physical properties.

immature pearl: Natural pearl that shows discoloration from a conchiolin core or darkened conchiolin rings.

imperial golds: South Sea pearls from the gold-lip pearl mollusk (Pinctada maxima) that exhibit deep gold color saturation.

Incomparable, The: See Peregrina, La.

indicator pearl: Small South Sea pearl (also known as a baby pearl) harvested from Pinctada maxima after six to eight months so a larger nucleus can be inserted in the existing pearl sac. The pearls are generally small and have thin nacre. Indonesia is the primary producer.

infrared spectroscopy: Method of determining the agents used to change the color of a cultured or natural pearl. It is also used to determine the chemical composition of imitation pearls.

interference: Interference of light by nacre creates the iridescent play of color on the surface of a pearl. Refraction, diffraction and/or thin-film interference occur as light penetrates extremely thin nacre layers.

iridescence: Play of color over the surface of a pearl as interference divides white light into its component colors.

irradiation: Exposing a cultured pearl to gamma rays darkens the nacre of a freshwater pearl or the freshwater mussel bead within a cultured saltwater pearl by affecting the manganese each contains.

Ise pearl: Natural white pearl from Ago Bay, Japan. Cultured akoya pearls eclipsed Ise pearls.

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Glossary of Pearl Terms H

Glossary of Pearl Terms H

H-grade pearl: Letter grade assigned to a high-grade pearl by Japan?s Pearl Inspection Office from 1952 to 1999.

half-drilled pearl: Pearl drilled to 2/3 or 3/4 of its diameter for setting in pearl jewelry.

half-light pearl: One of four Saxony quality factors used to describe natural German river pearls. See also: light pearl (highest quality), and sand and rotten pearl (lowest qualities).

half-round nucleus: Nucleus used to produce cultured blister pearls. A half-round nucleus has a domed side and a flat side; the latter is attached to the host?s shell.

Haliotis: Large genus of gastropods commonly known as abalone.

hamadera auction: First cultured akoya pearl auction, January 8, 1920, Osaka, Japan. Two kilograms of Mikimoto?s pearls were sold at the auction.

hama-age: Newly harvested cultured akoya pearls in Japan.

hama-age auctions: Annual auctions of newly harvested cultured akoya pearls in Japan.

hammer pearl: Brownish-black natural pearl produced by the hammer shell, Malleus malleus.

hanadama: Highest quality portion of a cultured akoya pearl harvest.

hanadama certification: Cultured akoya pearl certificate issued by the Pearl Science Laboratory of Japan indicating cultured akoya pearls that have the highest ratings in all quality attributes.

hankei: Japanese name for a cultured blister pearl.

hardness: Pearls range from 3.5 to 4.5 on the Mohs hardness scale.

harvest: Removing cultured pearls from mollusks on a pearl farm.

heat treatment: Applying heat to a natural or cultured pearl to improve its luster.

Heath pearls: Natural pearls from the Heath region of Scandinavia; popular in the latter half of the 19th century.

Hepu pearls: Natural pearls collected from Hepu and Behai in Guangxi Province, China, as early as the Han dynasty (206-220 AD).

hinge pearl: Natural pearl found near the hinge of a bivalve mollusk, typically of elongated, irregular shape.

hollow pearl: Natural or cultured pearl with a large, hollow cavity.

Hope Pearl: Natural marine blister pearl weighing 1,816 grains (454 carats), probably from Pinctada margaritifera.

hue: First impression of a pearl?s color.

hybrid mussel: Pearl mussel created by crossbreeding two species.

hypostracum: Mother-of-pearl layer of a pearl-bearing bivalve mollusk shell, the shell layer adjacent to the mantle.

Hyriopsis genus: Unionidae family mussels native to Southeast and East Asia. Pearl-producing species of the genus occur in China and Japan.

Hyriopsis cumingi: Triangle shell mussel native to China, used extensively in cultured freshwater pearl production.

Hyriopsis schlegeli: Biwa pearly mussel native to Japan, used to produce tissue-cultured freshwater pearls in Lake Biwa. Also used in China since the mid-1990s as a pure species and as a hybrid with Hyriopsis cumingi.

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Glossary of Pearl Terms G

Glossary of Pearl Terms G

gajamukta: So-called pearl said to come from the heads or tusk sockets of elephants; also called elephant pearl.

gajamuthu: Same as gajamukta and elephant pearl.

ganglia or ganglions, plural, ganglion, singular: Groups of nerve cells that make up the nervous system of a bivalve mollusk.

gastropod: Univalve mollusk, including land and sea snails, with a head and eyes.

gamma ray irradiation: Method of darkening freshwater pearls and the mother-of-pearl core of bead-nucleated saltwater pearls by altering the trace element manganese.

gem quality: Perfectly clean pearl exhibiting fine color and luster.

giant clam: Tridacna gigas, a non-nacreous natural pearl producer that is listed as a threatened species in Appendix II of the international CITES treaty.

giant clam nucleus: Bead nucleus formed from the shell of a giant clam. It is a violation of the international CITES treaty for any signatory nation to import or permit the use of wild giant clams for any purpose.

GIE Perles de Tahiti: (GIE = Groupement d?Interet Economique) Government organization responsible for regulating the Tahiti cultured pearl industry and promoting its products.

GIE Poe Rava Nui: Cooperative of Tahitian pearl producers and wholesalers.

GIA: Gemological Institute of America, nonprofit school and gemological laboratory founded in 1931; headquarters are in Carlsbad, California.

GIA pearl grading system: Grading system for cultured pearls; developed by GIA in the late 1990s.

glacier pearl: Imitation abalone pearl made from abalone shell.

glass nucleus: Bead used to produce imitation pearls like the Majorica brand.

glochidia: Freshwater mussel larvae.

gold-lip mollusk: Pinctada maxima mollusk used to produce of natural-color gold South Sea pearls. The outer edges of the shell interior are gold in color.

gonad: In saltwater bivalve pearl-producing mollusks, the reproductive organ where a bead nucleus or nuclei and donor-mollusk tissue piece or pieces are implanted to produce cultured pearls.

graduated strand: Strand of pearls with 3 mm or more gradation from the ends to the middle, with the largest pearl as the center.

graft tissue: Donor-mollusk mantle tissue piece implanted with or without a bead nucleus in a host mollusk to produce a cultured pearl.

graft: To insert a piece of graft tissue with or without a bead nucleus in a host mollusk to induce it to produce of a cultured pearl.

grain: Unit of weight associated with natural pearls. One grain equals 0.25 carat.

greffon: Term used in French Polynesia to describe the grafting process.

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Glossary of Pearl Terms F

Glossary of Pearl Terms F

Pearls Necklace Price

faceted cultured pearl: Pearl carved to create rhombic or triangular surface shapes that produce a sparkling optical effect when the wearer moves.

fancy colors: Most often associated with cultured freshwater pearls, consist of unusual colors like intense pink, orange or plum.

fancy shapes: Most often associated with cultured freshwater pearls, consist of unusual shapes like bars, crosses, letters, dragons and triangles.

faux pearl: Any imitation pearl.

feather pearl: Cultured pearl gown in the (fancy) shape of a bird feather.

feeding pearl: Legend in India that describes feeding a pearl to a rooster to let its digestive acids restore the original beauty of an old pearl.

first-generation cultured pearl: Freshwater or saltwater cultured pearl whose growth is started by implanting a tissue piece, or a bead nucleus and tissue piece, in a host mollusk that has not grown a pearl before.

fitaam: Wooden nose clamp used by natural pearl divers in the 19th century.

fjeris: Folk songs developed and sung by the pearl divers while on pearling ships in the 19th century.

flame structure: Optical effect commonly associated with conch pearls; produced by aragonite crystals arranged in two directions that are often intertwined.

floor system: Method of pearl farming used in Australia where mollusks are placed in baskets attached to posts or fences and left on the seabed.

flower pearl: Cultured freshwater pearl grown in the (fancy) shape of a flower.

folded crown mussel: Common name for Cristaria plicata, a freshwater mussel that?s also called the cockscomb mussel.

fossil pearl: Pearl that has fossilized and usually dates back to the Pliocene and Miocene periods.

free suspension: Method of pearl farming where mollusks are suspended in wire or nylon panels.

French dye method: Method of dyeing natural and cultured pearls using an organic coloring agent; originated in France.

French river pearl: Imitation pearl made from the hinge of Pinctada shells.

Freshadama pearls: Trade name for freshwater pearl strands composed of loose, gem-grade freshwater pearls exhibiting orient.

freshwater pearl: Pearl grown in a mussel in a non-saline environment.

fuhyu pearl: Chinese name for natural or cultured abalone pearl found or grown in Haliotis discus.

Fujita, Masao: Known as the father of the cultured freshwater pearl industry, Fujita was the first to culture whole freshwater pearls in Lake Biwa, Japan.

Fujita rose pearl: Freshwater pearl from Lake Biwa first developed and marketed by Dr. Masao Fujita in 1930. The pearls were produced by implanting a drilled mother-of-pearl bead and a donor-mussel tissue piece in the host mussel?s soft body.

funado: Kind of ama (Japanese pearl diver) who worked with a partner and a boat.

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Glossary of Pearl Terms E

Glossary of Pearl Terms E
Pearls Necklace Price

Edison Pearls: Large beaded freshwater pearls grown in the mollusc gonad in lieu of the mantle. See also Ming Pearls.

EDXRF: Energy dispersive X-ray fluorescence is a spectrometric method of determining chemical composition. It is used to differentiate cultured and natural pearls.

egg shape: Oval shape pearls.

EGL: European Gemological Laboratory.

Ehime Pearl Guild system: Point system developed in 1993 to give farmers exact information about how certain criteria are used to evaluate akoya pearls in Japan.

eightway roller: Perfectly round pearl.

elephant pearl: So-called pearl said to come from the heads or tusk sockets of elephants. See also gajamukta and gajamuthu.

endoscope method: Method of testing whether a pearl is natural or cultured; conducted by inserting a hollow needle into the drill hole of a pearl and examining the behavior of a ray of light projected through the hole and reflected from a small mirror at the end of the needle. The light reflects and bends with the concentric layers of a natural pearl and shines out the drill hole. The light enters the roughly parallel layers of a cultured pearl?s bead and travels through them to the surface.

epithelial cells: Cells on the shell side of a mollusk?s mantle tissue that produce mother of pearl and nacre.

epithelial graft tissue: Piece of mantle tissue from a donor mollusk implanted with a mother-of-pearl bead in the gonad or other body part of a host mollusk to produce a cultured pearl; or implanted with or without a bead in the mantle of a host mollusk to produce a cultured pearl.

essence d?orient: Paste made of several ingredients including scales from the undersides of certain fish. It is applied as a coating to glass beads to make imitation pearls; also called pearly essence.

exotic freshwater pearls: Cultured freshwater pearls that exhibit uncommon colors like green, gold, blue or orange.