Abalone pearl : Natural pearls forming in the mollusk Haliotis. These pearls usually have a blue iridescence while having a horn shape.
Akoya: Japanese name from akoya-gai given to cultured pearls from the mollusk Pinctada fucata martensii. They are known for their luster and exceptional quality
Aragonite: Natural crystalline form of calcium carbonate. Aragonite is one of the components of mother-of-pearl.
Baroque : Term used to describe pearls of irregular or asymmetrical shapes.
Biwa pearl: Pearl grown from the mollusk Hyriopsis schlegeli in Lake Biwa in Japan. This term is often incorrectly used to describe some freshwater pearls.
Bleaching : A process commonly applied to the majority of Akoya pearls and freshwater pearls. It is also occasionally used with South Sea pearls and Tahitian pearls.
Button pearl : Term used to qualify domed beads with a flat side.
Conchiolin : Organic substance acting as a glue to bind the calcite and aragonite crystals of mother-of-pearl.
Calcium carbonate : The main element making up the pearls (CaCO3)
Circle, pearl : Term defining the grooves or rings present on the pearl that can change the shape slightly or considerably.
Conch pearl : Non-pearly pearl of pink to orange-pink color produced by the mollusk Lobatus gigas. These pearls are very valuable because of their rarity and the fact that they cannot be grown. Also known as queen conch pearls, the most sought after will have a flame pattern on the surface.
Cortez pearl : Commercial name given to saltwater pearls grown in the Gulf of California, also called Sea of Cortez. These dark pearls, with a wide range of natural iridescence colors, are very expensive because of their rarity. Only a dozen necklaces of these pearls are produced each year.
Culture pearl : Generic term to identify pearls produced as a result of human intervention by insertion of a nucleus or a graft into a fresh or saltwater mollusk.
Dyeing : Method used to change the natural color of a pearl using different dyeing processes. In general, the beads are first drilled and then dipped in a liquid dye solution, which under pressure will be absorbed by the entire bead which has a porous texture. A tinted pearl that would be sliced in two would therefore have the same color on the inside as on the outside. This treatment is stable.
Freshwater pearl: Generic term used to describe all pearls grown in a mollusk living in an unsalted environment.
Generation (first, second, third, fourth) : This term, used for both freshwater and saltwater pearls, defines whether the pearl was the first developed in a mollusk or if it was developed in the same organism from which another generation of pearl had already been removed from the mollusk.
Hardness : The hardness of a pearl varies between 3.5 and 4.5 on the Mohs hardness scale.
Hybrid oyster : A variety of mollusks created by crossing various varieties of mollusks to obtain a mollusk capable of producing a particular type of pearl.
Irradiation : Treatment sometimes applied to certain cultured pearls consisting in exposing them to gamma rays in order to modify the color of the nacre of the pearls. The change occurs by a chemical modification of the manganese contained in the pearl's mother-of-pearl.
Iridescense : Property of the pearl to change color according to the angle of view or light.
Kasumiga : Japanese freshwater cultured pearl with nucleus that gets its name from Lake Kasumi-ga-ura in Japan. The pearls come from a cross between two types of freshwater mollusk and they are known for their particular color and iridescence. The majority of these pearls are now grown in China and are often sold under the name "Kasumi pearl", "Kasumiga like" or "Ming pearl".
Keshi : Japanese term meaning "poppy seed". Keshis are small, coreless, baroque pearls that were created by accident when the mollusk shell rejects the mother-of-pearl nucleus when culturing saltwater pearls. This term is also used to qualify the shape of some baroque freshwater pearls.
Luster : Term designating the quantity and quality of light reflected by the surface and the different layers of nacre. Luster is an important factor in the value and quality of a pearl.
Mabe : Type of pearl built (assembled) from a mother-of-pearl dome filled with resin, plastic or wax and closed behind another piece of mother-of-pearl so as to form a half-pearl. They can be grown in all types of pearl mollusks, although they are more common in black-lipped and silver-lipped oysters. Also sometimes called “pearl doublet”, these pearls are very fragile. The mother-of-pearl layer used is more or less thick and can crack after a shock. Their use on rings or bracelets is therefore not recommended.
Melo pearl : Natural pearl, yellowish color, non-nacred, found in melo melo shell.
Nacre : Interior coating of shiny-looking mollusks. Nacre, or mother-of-pearl, is also the outer component of the pearl.
Nucleus : Term representing the element inserted into the oyster to start the production of a pearl, often a piece of nacre.
Peacock : Term used to describe a particular natural color of Tahitian pearl varying from dark green-gray to blue-gray through pinkish and purplish hues. This term is also used to describe the dark color obtained during the irradiation of freshwater pearls, which may have green, bluish or reddish reflections.
Polishing : Action of polishing the pearl to improve the luster.
Rice pearl : Term describing freshwater pearls that have the shape and surface resembling the surface of rice.
Round : Term used for a pearl whose diameter does not vary in any place by more than 2%.
Saltwater pearl : Generic term used to describe all pearls grown in a mollusk living in a salty environment.
South sea pearl : Term representing natural pearls or cultured pearls produced by the mollusk Pinctada maxima. They are usually white, silver or golden.
Tahiti pearl : Pearls produced in French Polynesia in a salt water environment by the mollusk Pinctada margaritifera. They are dark in color, and can vary from very dark gray (almost black) to light gray tones through all the color ranges encountered in the color Peacock (green, pistachio, aubergine).