originally, the Japanese trade term for an assembled blister pearl grown in Pteria penguin; today, the word is used to describe any assembled blister pearl

Majorica pearls

imitation pearls created by coating a glass nucleus with essence d’orient, which is made from guanine crystals extracted from scales on the undersides of certain fish


organ lining the shell of freshwater and saltwater bivalve mollusks

mantle graft tissue

tiny piece of tissue cut from a donor mollusk’s mantle and implanted with or without a bead nucleus in a host mollusk to produce a cultured pearl


Greek and Latin word for pearl


genus name applied to a group of freshwater mussels, and the species name applied to the black-lip pearl mollusk

master set

group of pearls used for comparison to assess the quality characteristics of cultured pearls submitted for grading


matching pearls for uniformity in a strand or piece of finished jewelry

matinee length

pearl necklace measuring 20 to 24 inches (50 to 60 cm)

melo pearls

natural non-nacreous pearls found in the Melo melo marine gastropod


trade name for second or third grade Majorica imitation pearls

Mikimoto, Kokichi

first person to commercially produce spherical cultured pearls using the Mise-Nishikawa method of pearl culture

Miyoko pearls

imitation pearls marketed in Germany in 1983


any invertebrate from the phylum Mollusca


Japanese weight unit used to valuate cultured pearls (1 momme = 3.75 grams)


iridescent layer (principally calcium carbonate and conchiolin) lining the inner shell of some mollusk species; also called nacre when coating a bead to form a cultured pearl or composing a natural, tissue-cultured or keshi pearl


any of a number of bivalve mollusks with a brown or purplish-black shell