Glossary of Pearl Terms

Akoya cultured pearl: The industry term for cultured pearls produced in several species of saltwater oysters to include Pinctada fucata and Pinctada martensi. Akoya oysters are typically found in the cooler waters of Japan and China. Akoya pearls generally range in size from 2 mm to 10 mm and range in color from white, rose, cream, gold and blue/gray.

Baroque: An industry expression used to describe any pearl that is not symmetrical. Typically baroque pearls, whether cultured or natural, will be free form and asymmetrical.

Button: A shape of a pearl where one side of the pearl is slightly flat.

Choker: An industry standard length of a pearl necklace between 16 to 18 inches in length.

Collar: An industry standard length of a pearl necklace between 10 to 13 inches in length that usually rests in the middle of the neck. Collars are sometimes referred to as “dog collars” and are usually made up of two or more strands.

Color: A quality/value evaluation category used to describe the color of a pearl. Although color is not particularly an indicator of quality, generally creamy/yellow hues are less valuable than other pearl colors.

Cultured pearl: Any pearl which is grown by a mollusk that contains either a hard bead nucleus or soft tissue nucleus at its center, which has been surgically implanted in a mollusk by human means.

Freshwater cultured pearl: Any cultured pearl that is grown by a freshwater mollusk. Freshwater mollusks usually inhabit lakes and rivers, but they can be grown in ponds as well.

Grafting: The process of nucleating a mollusk to produce a pearl. Also termed as nucleation or implantation, grafting requires the human insertion of either a hard bead nucleus or soft mantle tissue into either the body of a mollusk or the mantle tissue of a mollusk. The nucleus or mantle tissue serves as a “seed” or “irritant” to produce a cultured pearl.

Luster: A quality evaluation category used to describe the combination of surface shine (reflectivity) and inner light refraction (depth). Lustre is perhaps the most important of all quality factors and is expressed in terms of high, medium and low lustre. The lustre of a high quality pearl should be bright and capable of sharply reflecting objects near its surface. A dull or chalky lustre indicates poor quality.

Mabe pearl: A half-spherical cultured pearl grown on the inside shell of a mollusk, as opposed to inside a mollusk’s body. Mabe pearls are grown by gluing a plastic hemisphere onto the inside of a mollusk’s shell. Once the hemispherical nucleus is covered with a sufficient amount of nacre, the pearl is cut away from the inner shell, the bead taken out, and the cavity filled with a substance such as epoxy resin and backed by a mother-of-pearl plate. Mabe pearls are sometimes referred to as blister pearls.

Matinee: An industry standard length of a pearl necklace between 20 to 24 inches in length.

Millimeter: A metric measurement of length used to determine a pearl’s size. Often expressed as “mm,” whereby one “mm” equals 1/25 of an inch.

Nacre: A calcium carbonate-based crystalline substance secreted by mollusks to form mother-of-pearl, pearls, and cultured pearls. Nacre secretion by a mollusk is usually a defense mechanism triggered by the intrusion of a foreign object into the body of an oyster.

Natural Pearl: A natural pearl is a pearl that develops without any human intervention.

Nucleus: Typically a small, round piece of polished shell from an American freshwater mussel used as an irritant or core in all saltwater cultured pearl production. In freshwater cultured pearl production, a nucleus is usually a small piece of soft mantle tissue from another freshwater mussel.

Nucleation: The process of nucleating a mollusk to produce a pearl. Also termed as grafting or implantation, nucleation requires the human insertion of either a hard bead nucleus or soft mantle tissue into either the body of a mollusk or the mantle tissue of a mollusk. The hard bead nucleus or soft mantle tissue serves as a “seed” or “irritant” to produce a cultured pearl.

Opera: An industry standard length of a pearl necklace between 28 to 32 inches in length.

Orient: Refers to a pearl’s iridescence.

Potato: Refers to a pearl with an oblong shape, such that it resembles a potato. Most potato pearls are freshwater cultured pearls from China.

Princess: An industry standard length of a pearl necklace between 17 to 19 inches in length.

Rice Pearl: A freshwater cultured pearl with a crinkled surface and elongated shape, such that it resembles a grain of rice. Most rice pearls originate from China or the United States.

Rope: An industry standard length of a pearl necklace over 45 inches in length.

Saltwater Pearl: Any pearl, natural or cultivated, that is grown in a mollusc that lives in salt ocean water.

Seed Pearls: Tiny natural pearls weighing under 1/4 grain, usually less than 2 mm in diameter.

Shape: A quality evaluation category used to describe the shape of a pearl. The most valuable pearls are round. However, other shapes of pearls include off-round, drop, oval, button (one flat side), circled, semi-baroque and baroque (asymmetrical/freeform). Freshwater cultured pearls are grown in all of the aforementioned shapes as well as stick, angel-wing, cross and coin (flat on two sides) shapes.

Size: A quality/price evaluation category used to describe the size of a cultured pearl. Size descriptions are expressed in millimeter and measured by the diameter of a pearl.

Sorting: The process of sorting pearls before matching and jewelry assembly to separate pearls by lustre, surface, shape, color and size.

South Sea cultured pearl: An industry name for large cultured pearls grown in the white-lip oyster (Pinctada maxima). South Sea cultured pearls generally range in size from 8 mm to over 22 mm in some cases and can range in color from white to gold, with silver, cream, and champagne in between.

Surface: A quality evaluation category used to describe the amount of blemishes on the surface of a pearl or cultured pearl. Surface descriptions range from clean (no visible blemishes) to heavily blemished.

Tahitian cultured pearls: Cultured pearls produced by the black-lip oyster (Pinctada Margaritifera) found in the atolls and lagoons of French Polynesia. Tahitian cultured pearls are natural in color and are produced in hues of silver, gray, green, orange, gold, blue, purple and black.