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.