Aragonite: A mineral similar to calcite in consisting of calcium carbonate, but differing from calcite in its orthorhombic crystallization, greater density and less distinct cleavage.

Biological mineralization: Interactive association of mineral and organic material that can lead to the development of complex structures such as nacre.

Biotope: A region uniform in environmental conditions and its population of animals and plants for which it is the habitat.

Byssus: A tuft of long tough filaments by which some bivalve mollusks, such as the Pinctada margaritifera oyster, adhere to a surface.

Calcite: A mineral consisting of calcium carbonate crystallized in hexagonal form and including common limestone, chalk and marble.

Calibrator: An instrument used to measure the size of pearls.

Cambrian: The earliest geologic period of the Paleozoic era during which most of organized beings were born and developed, including Nacre, which still exists today.

Clay Proteins: First organic-mineral grouping prior to the biological-mineralization process.

Conchioline: An ancient term used to describe all organic substance inside an oyster shell.

Gills: An organ that aquatic animals use for breathing underwater and for feeding in the case mollusks such as the Nacre.

Grafting: An extremely delegate surgical operation involving the voluntary insertion of a nucleus, or bead, into the host oyster. The nucleus becomes the heart of the cultured pearl.

Keshi: A sort of natural pearl made up entirely of mother-of-pearl and created by the oyster's premature rejection of the grafted nucleus.

Luster: The pearl's ability to reflect light, the intensity determining the pearl's shininess.

Mantle Tissue: This is the part of the oyster that secretes nacre.

Matching: Assorting pearls by size, shape and color in order to pair them for earrings or group them for a necklace.

Nacre: There are two meanings. First, it is a pearl oyster, a bivalve mollusk that secretes nacre, or, the second meaning, the mother-of-pearl substance.

Nacres de Plonge: Large older oysters, found on the bottom of lagoons. These oysters are used as the sires of pearl-producing oysters.

Natural Pearl: A pearl naturally formed in an oyster without human intervention.

Nucleus: A small, round bead created from the shell of a Mississippi River mussel. The bead is placed inside the pearl oyster during the grafting process.

Orient: This is the pearl's iridescence, its ability to reflect light from inside the pearl. Orient is a physical phenomenon involving the diffraction of light.

Oyster breeding facility: A specific installation at a cultured pearl farm reserved for oysters to lay their eggs for fertilization, producing larva that become baby oysters.

Pearl Sack: A sack created after the grafting process where the Nacre from the piece of mantle tissue from a donor oyster builds up in layers around the implanted nucleus, forming a cultured pearl.

Second Grafting: After an oyster has already produced a cultured pearl, another nucleus of the same size or larger is grafted into the pearl sack in hopes of another pearl being produced in two years.