G

gastropod

univalve mollusks with heads and eyes, including land and sea snails.

gem quality

perfectly clean pearl exhibiting fine color and luster

GIA

Gemological Institute of America, nonprofit school and gemological laboratory founded in 1931

GIA pearl grading system

 grading system for cultured pearls

giant clams

 also known as Tridacna gigas, they are non-nacreous natural pearl producers that are listed as a threatened species

gold-lip mollusk

Pinctada maxima mollusk used to produce natural-colored gold South Sea pearls

gonad

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

 the process of inserting a piece of graft tissue with or without a bead nucleus in a host mollusk to induce the production of a cultured pearl

graft tissue

donor-mollusk mantle tissue piece rooted with or without a bead nucleus in a host mollusk to produce a cultured pearl

grain

 unit of weight associated with natural pearls