Akoya Cultured Pearl: Pearls produced by deliberate human intervention in varieties of saltwater mollusks generally found in the waters around Japan and China. Colors range from cream, white, rose, gold and blue-gray.

Baroque: A cultured pearl that is asymmetrical and free form in shape.

Biwa Pearl: A cultured pearl cultivated in a freshwater mussel in Lake Biwa, in Japan. The term also refers to any pearl cultivated in a freshwater mussel in Japan.

Blemish: Defect found on the surface of the pearl. Can be non-damaging with spots, bumps, pits and wrinkles or damaging with cracks, holes and chips.

Clean: Describes the absence or relative absence of any blemishes on the surface of a pearl.

Conch Pearl: Pearls produced by a conch, a saltwater mollusk from tropical waters. Similar in color to pink coral.

Cultured Pearl: Pearl grown in a mollusk that has been surgically implanted with an irritant, through human intervention.

Cultivated Pearl: Same as cultured pearl.

Freshwater Cultured Pearl: A cultured pearl cultivated in a freshwater mollusk from a lake, river or pond.

Grafting: The insertion of an irritant into the body or the mantle tissue of a mollusk, through human intervention, in order to produce a cultured pearl.

Imitation Pearl: Man- or machine-made pearls.

Keshii Pearl: Non-nucleated pearls produced accidentally as a by-product of the cultivating process. Also known as seed pearls and not considered a natural pearl.

Luster: The radiance of a pearl. The greater the luster the greater the value.

Mabe Pearl: Dome-shaped cultured pearls that are cultivated on the inner shell of a mollusk rather than in its body.

Matching: Using the parameters of luster, surface, shape, color and size to match one pearl with another to create a piece of pearl jewelry, such as a necklace.

Nacre: A calcium carbonate-based crystalline substance secreted by a mollusk as a defensive device against the intrusion of a foreign irritant into its body.

Seed pearls: Tiny naturals weighing under 1/4 grain, usually less than 2 millimeters in diameter.

Semi-cultured: Imitation pearls.

Shape: A quality evaluation, describing the shape of a pearl. While round is the most prized shape, saltwater and freshwater pearls are produced in a variety of shapes and colors.

Size: The diameter of a pearl measured in millimeters and used for quality and price evaluation.

Sorting: Separating pearls by surface, shape, color and size prior to the jewelry matching process.

South Sea Cultured Pearl: Large pearls cultivated in the white-lip oyster. These range in the shades of white, gold, silver, cream and champagne.

Surface: A quality evaluation of the amount of blemishes on a pearl, ranging from clean to heavily blemished.

Tahitian Cultured Pearl: Cultured pearls cultivated in the black-lip oyster found in French Polynesia. These come in the shades of black, silver, gray, green, orange, gold, blue and purple.

Wild pearl: Natural pearls.