
- Abalone Blister PearlNatural half-pearl that forms on the inside of an abalone oyster shell rather than within its tissue. Once it is reworked, it is known as a Mabe pearl.
- Abalone PearlNatural whole pearl formed in the body of an abalone, a univalve mollusk known for its iridescent pearls.
- AdductorMuscle responsible for opening and closing a mollusk shell. Sometimes eaten as a delicacy.
- Akoya Cultured PearlA pearl produced by inserting a seed into a Pinctada fucata martensi mollusk.
- AmaHistorical female pearl divers of Japan. There are 2 kinds: kachido worked alone while the funado worked with a partner, usually the husband.
- AragoniteCalcium carbonate crystals that are stacked in a brick pattern. Aragonite is a component of mother-of-pearl and nacre.
- AtollA ring of coral that encircles a lagoon. Atolls are considered to be the best place to farm the Pinctada margaritifera mollusk.
- BaroqueAn irregular or asymmetrical pearl. Freshwater pearls are commonly baroque in shape because they are seeded with tissue rather than a bead.
- Basra PearlName given by Indian pearl dealers to freshly harvested natural pearls from the town of Basra, Iraq.
- Bead-Cultured PearlA pearl grown in freshwater or saltwater that has been started by implanting a bead into a mollusk.
- BivalveA mollusk with a two-part shell attached by a hinge. Some but not all bivalve mollusks produce pearls.
- Biwa PearlA freshwater pearl grown in a Hyriopsis schlegeli mussel in Lake Biwa, Japan. Sometimes used incorrectly to describe any freshwater pearl.
- Black-Lipped Pearl OysterA pearl-producing mollusk that is either a Pinctada margaritifera or a Pinctada margaritifera cumingi.
- Black PearlA pearl that is naturally dark in color produced by any of the following mollusks: Pinctada margaritifera, Pinctada mazatlanica, or Pteria sterna.
- BleachingCommon whitening treatment applied to most freshwater and cultured Akoya pearls, and sometimes to Tahitian or South Sea pearls.
- BlemishA flaw on the surface of a pearl, including pits and/or humps. Blemishes may be difficult to detect with the naked eye.
- Blister PearlA pearl that is attached to the shell of the mollusk. It may occur naturally or be done intentionally.
- BuHistorical Japanese linear measurement that is still used today to describe the diameter of a bead nucleus. One bu = 3.03 millimeters.
- BuffingA method of removing organic residue from the surface of a pearl to improve its appearance.
- Button PearlA dome-shaped pearl with one flat side. Classified as ‘high’ or ‘low’ based on height of dome.
- ByssusThread-like tissue secreted by bivalve mollusks to attach themselves to a solid surface.
- Calcareous ConcretionMany types of mollusks including oysters and conches produce these stone-like growths. All pearls are calcareous concretions, nacreous or otherwise.
- CalciteA natural crystalline form of calcium carbonate. When combined with conchiolin and aragonite, they make up nacre.
- CaratA weight measure sometimes used for natural pearls. A carat = 4 grain, 200 milligrams and 0.007054 ounces.
- ChokerA pearl necklace that lies above the collar bone and measures 14-16-inch (35-41 cm) in length.
- Circled PearlA pearl with raised, concentric rings on its surface, likely due to the pearl rotating during growth.
- Clam PearlsNon-nacreous pearls sometimes found in clams. They are generally low in value.
- CleanThe best way to clean pearls is by wiping them with a soft cloth after each wear. Use a damp cloth and mild dish soap only when needed. Let dry before storing.
- CoatingA natural or artificial layer applied to pearls to enhance surface quality, luster or other optical effects.
- CollarA pearl necklace measuring 10-13-inch (25-33 cm) in length, slightly longer than a choker.
- ColorPearls come in a rainbow of colors, from classic white to exotic black and every shade in between. Pearls frequently have overtones or a secondary color, including rose, silver, gold, and peacock (a mix of rose, gold, and green).
- Composite PearlsTwo conjoined pearls that give the appearance of a single pearl.
- Conch PearlA non-nacreous pearl produced by a conch shell. Rare and valuable, pink is the most desired color.
- ConchiolinAn organic glue-like substance that bonds aragonite and calcite crystals in a mollusk’s shell and creates the iridescent layer of mother-of-pearl.
- Cortez PearlsPearls cultured in Pteria sterna mollusks in the Sea of Cortez, aka the Gulf of California.
- Cultured PearlA pearl produced by inserting a bead or tissue graft into a mussel or mollusk. The main difference between cultured pearls and natural pearls is cost, cultured being more affordable.
- DiffractionOne way nacre layers split light into rainbow colors, sometimes displayed as an overtone.
- DomeA rounded, convex shape with a flat back that is thickest in the middle and tapers toward the edges.
- DyeingArtificial coloring of pearls to enhance hue, or to create pearls in colors not found in nature. Pearls are usually dyed after drilling to improve color absorption.
- Faux PearlAny imitation pearl manufactured by coating a glass or plastic sphere with a pearlescent coating that is sometimes pearl powder.
- FluorescenceA common diagnostic tool used to determine whether a pearl has been dyed.
- Freshwater Cultured PearlA pearl produced by inserting a bead or tissue graft into a mussel that lives in non-saline water.
- Freshwater PearlA pearl grown in a mussel that lives in non-saline water. Freshwater pearls tend to have a more freeform shape than saltwater pearls.
- GajamuktaPearls said to come from the tusk sockets of elephants.
- GastropodA type of univalve mollusk with a head and eyes, including land and sea snails.
- Gold-Lip OysterThe Pinctada maxima mollusk that produces gold South Sea pearls. The edges of the shell’s interior are golden in color.
- GonadThe reproductive organ of pearl-producing mollusks where the bead or tissue graft is implanted to produce cultured pearls.
- Graduated StrandA strand of pearls in which the pearls increase in size a minimum of 3 mm from end to middle, with the largest at the center.
- GraftThe insertion of tissue into a mollusk to produce a cultured pearl.
- GrainA unit of weight used with natural pearls. One grain = 0.25 carat.
- GreffonFrench Polynesian term to describe the grafting process.
- Half-DrilledA pearl that has been drilled to 2/3 or 3/4 of its diameter in order to be set in a piece of jewelry.
- HaliotisThe type of gastropod more commonly known as abalone. The shell is extremely strong with tiny tiles of calcium carbonate stacked like bricks.
- HankeiThe Japanese term for a cultured blister pearl, which is a pearl attached to the inner surface of a mollusk shell.
- Hyriopsis SchlegeliThe pearl mussel native to Japan used to produce cultured freshwater pearls in Lake Biwa. Also cultivated in China.
- Imitation PearlAny artificial pearl created by coating a glass or plastic sphere with a pearlescent coating that is sometimes pearl powder.
- InterferenceInterference of light by nacre creates a variety of colors on a pearl’s surface.
- IridescenceColor play on the surface of a pearl caused by light being split into its component colors.
- IrradiationA process in which a cultured pearl is exposed to gamma rays to darken the nacre.
- KanHistorical Japanese unit used to weigh pearls. One kan = 1,000 momme, 3.75 kilograms or 8.26 pounds.
- Keshi PearlA small natural or cultured pearl. The term comes from the Japanese word for ‘poppyseed.’
- La Paz Pearl OysterBefore culturing black-lip pearl oysters in French Polynesia became popular, most black pearls came from La Paz Pearl Oysters in Panama or Baja California.
- La PeregrinaA natural drop-shaped pearl found in 1513 in the Gulf of Panama by the Spanish explorer Balboa and given to King Philip II of Spain.
- Linné, Carl VonCarolus Linnaeus was the first person to culture whole pearls. He also created the classification system of plants and animals used today.
- Longline SystemsPart of the pearl farming process. Lines are stretched between buoys and anchored to the bottom at both ends. Vertical lines (chaplets) with baskets of mollusks are suspended from the longlines.
- LusterThe quality and quantity of light reflected from the surface of a pearl. High-quality pearls appear to be illuminated from within. Thicker nacre usually results in better luster.
- MabeA blister pearl grown in Pteria penguin mollusk, then hollowed out and filled with a substance and backing.
- Maeshori TreatmentA deep-cleaning process used in Japan before bleaching Akoya cultured pearls. Also used to describe several processes used to enhance the luster of most Chinese Freshwater and some South Sea pearls.
- MantleThe organ that lines the shell of bivalve mollusks and secretes nacre.
- Margaritifera / margaritiferaWith a capital ‘M’, a genus of freshwater mussels. With a lowercase ‘m’ (Pinctada margaritifera), a species of black-lip mollusk.
- MatchingRefers to a strand in which the pearls are uniform, either in graduated size or all the same size.
- MatineeA pearl necklace measuring 20-24 inches (50-60 cm) in length. Matinees have a slimming effect. It is the classic length for an Akoya pearl necklace.
- Melo MeloMarine gastropod that produces the non-nacreous Melo pearl. Rare and very valuable.
- Mikimoto, KichimatsuFirst person to commercially produce round cultured pearls using the Mise-Nishikawa method.
- MolluskA large and diverse category of invertebrates, some of which produce pearls.
- MommeA Japanese unit of weight for cultured pearls. One momme = 3.75 grams.
- Mother-of-PearlThe iridescent lining of the inner shell of some mollusks. When it coats a bead to form a cultured pearl, it is called nacre.
- NacreThe lovely iridescent substance that forms inside a mollusk and is commonly called mother-of-pearl. Made of aragonite, calcite and conchiolin.
- Natural PearlA pearl that has formed in a mollusk without human intervention. Very rare and thus valuable.
- Nautilus PearlExtremely rare pearl from the Nautilus pompilius. Imitation Osmenda pearls are sometimes incorrectly named nautilus pearls.
- Nishikawa, TokichiCredited, possibly by mistake, with discovering the bead-and-tissue method of pearl culture.
- Non-Nacreous PearlA natural pearl lacking a nacreous surface. Non-nacreous pearls appear to be denser and more like porcelain.
- NucleationThe process of implanting a bead in a mollusk to become the core of a cultured pearl.
- NucleusThe bead implanted into a mollusk to form the core of a cultured pearl. The most common nucleus is a mother-of-pearl bead.
- OperaA pearl necklace measuring 28-35 inches (70-90 cm) in length. Dramatic and meant for glamorous evening events, opera length necklaces can be worn as a long single strand or doubled.
- Organic DyesUsed to alter the color of cultured and natural pearls. Organic dyes may produce a more original effect, but can be difficult to replicate.
- OrientAn optical phenomenon producing iridescence in some pearls. Diffraction, refraction, reflection and thin-film interference may all cause orient.
- Oriental PearlHistorical term for natural pearls from the Red Sea and Persian Gulf.
- OvertoneSecondary color on the surface of a pearl created by the nacre splitting light into component colors.
- OysterCommon name for some bivalve mollusks. True oysters do not create nacreous pearls.
- PeacockHue commonly associated with black pearls. Colors range from dark green-gray to blue-gray with rose and purple overtones.
- PearlA smooth, lustrous mass formed in certain bivalve mollusks and valued as a gem.
- Pearl SacGrown to contain an intruder or implanted bead, it deposits nacre to form a pearl.
- PeelingRemoving the outer nacre layers of a cultured pearl to improve quality.
- Pelegrina, LaA pair of natural pearls with the same name. The first is round and weighs 111.5 grains; the second is drop-shaped and weighs 133.2 grains.
- Pinctada Fucata MartensiMollusk which produces Akoya pearls. Akoyas were the first pearls to be cultured, which took place in Japan in the 1920s.
- Pinctada ImbricataA general term that encompasses all Akoya mollusks regardless of where they grow.
- Pinctada MargaritiferaBlack-lip mollusk that produces Tahitian and Cook Island cultured pearls.
- Pinctada MartensiSynonym for Pinctada fucata martensi, a mollusk that produces Akoya pearls.
- Pinctada MaximaThe silver- or gold-lip pearl mollusk used to produce South Sea cultured pearls.
- Pinctada MazatlanicaMollusk native to the Gulf of California and the Pacific Ocean in Mexico and Central America.
- Pinctada RadiataPearl-producing mollusk with a wide distribution, living in both hemispheres and most oceans and seas around the world.
- PrincessA pearl necklace measuring 17-19 inches (43-48 cm) in length. A modern classic, princess length necklaces are extremely versatile and elegant as they go effortlessly from day to evening.
- Red TideOverproduction of algae, also called algal bloom, that can weaken or kill mollusks by consuming all the oxygen in the water and/or poisoning them when the algae die. Red tide is not a true tide, nor is it always red.
- Refractive Index (RI)The measurement of light as it bends from one substance to another, such as from air into nacre. The refractive index of natural and cultured pearls is 1.51-1.66.
- Rice PearlA small, oblong pearl that resembles a grain of rice. Rice pearls are often strung together in multiple strands.
- RopeA pearl strand measuring more than 45 inches (115 cm) in length. A luxurious length that offers multiple options including looping and knotting.
- Saltwater PearlA natural or cultured pearl produced by a mollusk living in saltwater. Usually round, saltwater pearls often have a thinner nacre coating than freshwater pearls, which are almost entirely nacre.
- SautoirA pearl strand measuring more than 36 inches (90 cm) in length. A sautoir is also sometimes called a rope.
- Scallop PearlA non-nacreous pearl produced by a mollusk of the Pectinidae family. Scallops can swim and are the only migratory bivalve.
- Seed PearlA tiny natural pearl weighing less than 1/4 grain and usually measuring less than 2 mm in diameter.
- ShapePearls come in a wide variety of shapes, including round, ringed, button, drop and baroque.
- Shell PearlImitation pearl made from a mollusk shell, aka mother-of-pearl. The nacre is pulverized and mixed with other materials to form a pearl.
- ShinjuJapanese word for pearl. The method for culturing pearls was developed in Japan in the 1920s.
- SizeDescribes the diameter of a pearl. Anything below 7 millimeters is called ‘dainty’; 7 to 8 millimeters is a classic ‘wear anywhere’ size; while those greater than 8 millimeters are considered to be ‘luxury.’
- South Sea PearlPearl produced by the Pinctada maxima mollusk. Usually larger than the average pearl, South Sea pearls tend to be exceptionally smooth and round, making them highly desirable.
- SpatSaltwater mollusk larva that is old enough to attach itself to a fixed surface but does not yet have a shell.
- Strombus GigasAlso called the queen conch, a large mollusk that lives in the Caribbean. Pearls correspond to the color of the inner surface of the shell and are very rare.
- SurfaceOne of the factors considered when determining the quality of a pearl. A strand of pearls without blemishes is very rare.
- Tahitian Cultured PearlProduced in French Polynesia by the black-lip (Pinctada margaritifera) mollusk.
- TintingDiluted dye that produces a slight change in a pearl’s color, often pink.
- ToneA synonym for color, meaning the main color of a pearl. Overtones are secondary colors seen in a pearl.
- TreatmentAny action other than polishing that alters a pearl’s appearance, including bleaching, heating, waxing, irradiation, drilling, working and cutting.
- UnioA species of freshwater mussel, many of which produce small, irregular pearls with good luster.
- WaxingA type of treatment used to enhance a pearl’s luster. Sometimes called ‘maeshori.’
- WorkingThe removal of nacre layers from a pearl to improve its appearance. Luster treatments such as working can be difficult to detect with the naked eye.