Here's a list of Pearl-Guide.com terms that might help you understand the site's terminology better, as well as the discussions within the community forum. It is compiled from multiple sources, and we believe it to be one of the most comprehensive lists available on the subject.


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Abalone: A group of ancient marine gastropods (snails) that have a unique, flattened shell with small holes (gonopores), that inhabit many of the world's temperate waters. Their shells display beautiful and iridescent mother of pearl shell. The family is Haliotidae and the genus is Haliotis.

Abalone blister pearl: Nacreous natural half-pearl formed on the inside of an abalone shell.

Abalone cultured blister pearl: Nacreous pearl cultured by attaching a half-round nucleus to the inside of the abalone shell. At harvest, the shell is cut around the blister, leaving the nucleus and shell intact.

Abalone Mabe pearl: Nacreous cultured blister pearl that is separated from the shell at harvest. Its half-round nucleus is removed, the cavity is filled with epoxy resin and backed with a mother-of-pearl disk.

Abalone pearl: Nacreous natural whole pearl formed in the body of an abalone.

Abas: Unit of weight historically used in Persia to valuate natural pearls. One abas is equivalent to 0.91 carat.

Abernethy Pearl: Discovered by Bill Abernethy in Scotland in 1967. This natural freshwater pearl weighs 44 grains.

Abyadh: Historical Persian quality factor for the best color natural pearl (white color).

Acid test: Method of testing the authenticity of a natural or cultured pearl with hydrochloric acid. Pawnbrokers often use this destructive test.

Adductor muscle: The muscle that closes a bivalve mollusk's two shells; it is considered a delicacy in many locations and sometimes referred as "pearl scallop", "pearl meat" and "callo".

Ago Bay, Japan: The location of the Mikimoto's first pearl farm and still the home of many akoya farms today.

Akoya-Gai: The Japanese name of the Pinctada imbricata (=fucata/radiata) pearl oyster used in Akoya pearl production.

Akoya keshi: small pearl found in the Akoya mollusk where it forms as a byproduct of the pearl culturing process.

Akoya pearls: Natural or cultured pearls from an Akoya pearl oyster.

Alabaster pearl: Imitation pearl made from an alabaster bead that is coated with iridescent lacquer.

Ama: The traditional female pearl divers of Japan. There were two types: the kachido (those who worked alone) and the funado (those who worked with a partner on a boat, typically the husband).

Amami Gold Pearl: Pearls first produced by the Tasaki Shinju Company in the Pinctada maxima mollusk on the Ryukyu Islands of Japan; known for its better-than-average luster.

American pearls: Natural and cultured pearls found or grown in the waters in and around the Americas.

Aniline dyes: Synthetic organic (contain carbon) agent used to artificially produce dark colors in cultured pearls.

Antilles pearls: Imitation pearls made from the spindle of trochus or turban shells.

Aragonite: Calcium carbonate crystals stacked in a brick-like pattern; a component of nacre and mother-of-pearl.

Atlas pearl: Imitation pearls made from atlas spar.

Atoll: A ring of coral that nearly encircles an island lagoon. Atolls are considered the best place to farm cultured pearls in the Pinctada margaritifera mollusk.

Atrina pearls: Dark pearls produced by "Pen shells" of the genus Atrina in the Gulf of California, Mexico.

Awabi pearls: Japanese abalone pearl found in the gastropod Auris marina.