Pearl Glossary of Terms
A•B•C•D•E•F•G•H•I•J•K•L•M•N•O•P•Q•R•S•T•U•V•W•X•Y•Z
We have included the list of many Pearl terms and definitions below to help you understand and learn more about pearls.
A
abalone blister pearl: Nacreous natural half-pearl formed on the inside of an abalone shell.
abalone cultured blister pearl: Nacreous pearl cultured by attaching a half-round nucleus to the inside of the abalone shell. At harvest, the shell is cut around the blister, leaving the nucleus and shell intact.
abalone mabe pearl: Nacreous cultured blister pearl that is separated from the shell at harvest. Its half-round nucleus is removed, the cavity is filled with epoxy resin and backed with a mother-of-pearl disk.
abalone pearl: Nacreous natural whole pearl formed in the body of an abalone.
abas: Unit of weight historically used in Persia to valuate natural pearls. One abas is equivalent to 0.91 carat.
Abernethy Pearl: Discovered by Bill Abernethy in Scotland in 1967. This natural freshwater pearl weighs 44 grains.
abyadh: Historical Persian quality factor for the best color natural pearl (white color).
acid test: Method of testing the authenticity of a natural or cultured pearl with hydrochloric acid. This destructive test is often used by pawnbrokers.
adductor: The muscle that opens and closes a bivalve mollusk’s two shells; it is sometimes cooked, eaten and considered a delicacy.
Ago Bay, Japan: The location of the Mikimoto’s first pearl farm and still the home of many akoya farms today.
akoya: The Japanese name (akoya-gai) of the Pinctada fucata martensi mollusk used in cultured akoya pearl production.
akoya keshi: Small pearl found in the akoya mollusk where it forms as a byproduct of the pearl culturing process.
akoya pearls: Natural or cultured pearl from an akoya mollusk.
alabaster pearl: Imitation pearl made from an alabaster bead that is coated with iridescent lacquer.
ama: The historical female pearl divers of Japan. There were two types: the kachido (those who worked alone) and the funado (those who worked with a partner from a boat, typically the husband).
Amami Gold Pearl: Pearl first produced by the Tasaki Shinju Company in the Pinctada maxima mollusk on the Ryukyu Islands of Japan; known for its better-than-average luster.
American pearls: Natural pearls found and cultured pearls grown in the waters in and around the Americas.
aniline dyes: Synthetic organic (contain carbon) agent used to artificially produce dark colors in cultured pearls.
Antilles pearls: Imitation pearls made from the spindle of trochus or turbo shells.
aragonite: Calcium carbonate crystals stacked in a brick-like pattern; a component of nacre and mother-of-pearl.
atlas pearl: Imitation pearl made from atlas spar.
atoll: A ring of coral that nearly or wholly encircles a lagoon. Atolls are considered the best place to farm cultured pearls in the Pinctada margaritifera mollusk.
Atrina pearls: Dark pearl produced by Atrina vexillum in the Gulf of California.
awabi pearls: Japanese abalone pearl found in the gastropod Auris marina.
B
baby pearl: Also called “indicator pearl.” South Sea pearl from Indonesia grown for a short period to produce a pearl sac. The nacre is typically very thin and the quality low.
baroque: A pearl shape; irregular and not symmetrical.
Basra pearl: Named after the town of Basra in Iraq. Name given by Indian dealers to freshly harvested natural pearls from this area.
baten: Historical Persian quality factor describing a button pearl.
baythawee: Historical Persian quality factor describing an oval pearl.
bead-and-tissue-cultured pearl: A freshwater or saltwater cultured pearl whose growth is started by implanting a shell bead nucleus and a donor-mollusk mantle-tissue piece in the mantle, gonad, or other body part of a host mollusk.
bead-cultured pearl: A freshwater or saltwater cultured pearl whose growth is started by implanting a shell bead nucleus in an existing pearl sac from which a first-generation cultured pearl was removed.
bell pearl: Historical term used to describe a natural, pear-shaped pearl.
Big Pink Pearl: Listed in Guinness Book of World Records as largest natural abalone pearl from the Haliotis rufescens, weighing 469.13 carats.
Bironite: Trade name for a non-organic nucleus composed of dolomite.
bivalve: A mollusk from the class Bivalvia having a two-part shell attached by a hinge.
Biwa pearl: Pearl grown in Hyriopsis schlegeli freshwater mussel in Lake Biwa, Japan. Term is often incorrectly used to describe freshwater pearls in general.
Biwako pearl: The name first given to a Biwa pearl.
black-lipped mollusk: Pinctada margaritifera and Pinctada margaritifera cumingi mollusk.
black pearl: A pearl of naturally dark colors produced by the Pinctada margaritifera, Pinctada margaritifera cumingi, Pinctada mazatlanica and Pteria sterna mollusks.
bleaching: A common whitening treatment applied to most cultured akoya and freshwater pearls, and occasionally applied to cultured South Sea and Tahitian pearls.
blinking: An optical phenomenon created by light reflecting from mother-of-pearl remnants on the shell bead within a cultured pearl. Blinking often proves a cultured pearl is bead-nucleated and often indicates a thin nacre coating.
blister pearl: Pearl attached to the shell of the host mollusk. These can occur naturally when a pearl sac bonds with the upper mantle or by human intervention when a hemispherical nucleus is attached to the inner shell by a grafting technician.
blue pearl: Name given to a cultured mabe pearl grown in the Haliotis iris abalone shell.
bodycolor: The aspect of a pearl’s color that is caused by pigment as opposed to light interference.
Bourgignon pearls: Imitation pearls popular in 18th and 19th century France.
brailing: Technique of using a row of hooks to drag the bottoms of southeastern US rivers to collect mussels.
Brewster’s theory: Developed in 1814 by Sir David Brewster, it attributed the iridescent colors of mother-of-pearl to light diffraction from the surface structure.
Broome pearl: Australian cultured South Sea pearl of the 1960s, exhibited a silver hue.
bu: Historical Japanese linear measure still used today to designate the diameter of a bead nucleus. One bu equals 3.03 mm.
Buddha pearl: The first cultured blister pearl produced by the Chinese by implanting a Buddha-shaped nucleus between the mantle and shell of freshwater mussels in the late 1200s.
buffing: A post-harvest method of removing organic residue from pearls and polishing their surface.
buoys: Used to float lines from which mollusks are hung in net panels or other holding devices.
Burmese pearl: Historic term given to a natural Pinctada maxima pearl with a golden or yellow hue.
burnt gold: Also called burnt orange. The most desirable color of gold South Sea pearls; they exhibit a deep gold to dark orange or reddish bodycolor.
button pearl: A dome shape pearl with a flat side. Button shapes are classified as high or low depending on the height of the dome.
byssus: Structure composed of thread-like tissue that bivalve mollusks use to anchor themselves to a solid external surface.
C
cabochon: In gemology, a usually round or oval shaped gemstone with a domed top and flat bottom; hence, a pearl of that shape.
calcareous concretion: Whether nacreous or not, all pearls are calcareous concretions.
calcite: A crystalline form of natural calcium carbonate that, together with aragonite and conchiolin, makes up the structure of nacre.
calcium carbonate: Pearls are composed of calcium carbonate (CaCO3) and other elements and substances.
candling: Examining a pearl in front of a focused light source to determine if it shows the layered structure that proves it contains a bead nucleus.
carat: A weight measure sometimes used for natural pearls. It equals 4 grains, 200 milligrams or 0.007054 oz.
Cassis pearl: Yellowish brown pearl produced by gastropods of the genus Cassis.
cave pearls: Stalactite pearls of a brown color, concentric layers and, sometimes, a pearly luster.
Ceylon pearl mollusk: The Pinctada radiata mollusk known for producing natural pearls in the Gulf of Mannar, the Red Sea and the Persian Gulf. According to some taxonomists, Pinctada radiata is a synonym for Pinctada imbricata, Pinctada fucata and others.
chau: Historical unit of weight used in the natural pearl trade in India, also called chov.
chaplets: Line extensions of a pearl farm’s long line system that are secured to the shells.
chemical dyes: A method used to alter the natural color of a cultured pearl.
cherry: A reddish overtone often found on pearls produced by Pinctada margaritifera.
chloride vapor deposition: A superficial pearl coating/coloring agent experimented with in the 1960s.
choker necklace: A strand of pearls that lies above the collar bone, 14 to 16 inches in length (35 to 41 cm).
chov: See chau.
CIBJO: (Confédération Internationale de la Bijouterie, Joaillerie et Orfèvrerie), also known as the World Jewellery Confederation, is an international confederation of jewelry, gemstone, horology, and silverware trade organizations. CIBJO publishes The Pearl Book: Natural, Cultured & Imitation Pearls—Terminology & Classification.
circled pearl: Pearl with raised concentric rings around its surface, thought to be produced by the developing pearl rotating during growth.
clam pearl: Non-nacreous pearl found in clams.
coating: A layer of artificial or natural substance applied to pearls to enhance luster, surface quality or to produce other optical effects.
coconut pearl: So-called “pearl” said to be found in coconuts.
coin pearl: Bead-and-tissue-cultured pearl shaped like a coin.
collar: A strand of pearls that measures 10 to 13 inches (25 to 33 cm).
composite cultured blister pearl: See mabe.
composite pearl: Two separate pearls conjoined to give the appearance of a single pearl.
concentric structure: The layering of calcium carbonate crystals that is characteristic of natural pearls, tissue-cultured pearls, bead-cultured pearls and the nacre layer of bead-and-tissue-cultured pearls.
conch pearl: Non-nacreous pearl produced by the conch shell.
conchioline: The organic substance that acts like glue, binding calcite and aragonite crystals together.
condari: Historical Chinese unit of weight used to evaluate pearls; associated with the weight of a grain of wheat or rice.
cool hues: Colors from reddish purple to greenish blue to yellowish green from the GIA color reference chart.
coque de perle: Imitation pearl made from the Nautilus shell (also see Osmenda pearl).
corn flake shape: Second generation pearl that the Chinese mistakenly call “keshi.” They are shaped like breakfast cereal corn flakes.
Cortez pearls: Trade name forthe pearl cultured in Pteria sterna in the Gulf of California, which is also called the Sea of Cortez.
CP&J City: China Pearls and Jewellery City. The world’s largest pearl and jewelry trade center; under construction in Shanxiahu, Zhuji, Zhejiang, China. The first phase opened in April 2008.
Cristaria plicata: The cockscomb mussel first used in Japan and China in cultured freshwater pearl production.
cross shape: Tissue-cultured pearl grown in the shape of a cross.
cultured pearl: Pearl produced by the human insertion of a bead, a tissue graft, or a bead and tissue graft in a freshwater mussel or saltwater mollusk.
D
dadjin: A 19th-century pearler’s basket used to hold mollusk shells and a knife.
dana: Historical Persian quality factor describing a perfect round natural pearl larger than 7 mm.
diffraction: One of the ways nacre layers interfere with light, possibly causing light to split into its component colors (the spectrum), one or more of which can be displayed as overtone and/or orient.
Dobo pearl: An Indonesian Pinctada maxima pearl grown on the Aru Island of Wokam prior to World War II. It is said that 9 mm cultured akoya pearls were used as nuclei.
dolomite nucleus: See Bironite.
Domé: Trade name for cultured American blister pearl produced with a nucleus that remains in the blister when the shell is cut around the pearl’s perimeter.
drop: A symmetrical pearl shape that’s round on one end and tapers almost to a point on the other. The shape can be short or long and takes its name from a water drop or teardrop.
dust pearl: Historical term describing a natural pearl smaller than 2 mm. See seed pearl.
dyeing: Artificially coloring pearls using a dye.
E
EDXRF: Energy dispersive X-ray fluorescence is a spectrometric method of determining chemical composition. It is used to differentiate cultured and natural pearls.
egg shape: Oval shape pearls.
EGL: European Gemological Laboratory.
Ehime Pearl Guild system: Point system developed in 1993 to give farmers exact information about how certain criteria are used to evaluate akoya pearls in Japan.
eightway roller: Perfectly round pearl.
elephant pearl: So-called pearl said to come from the heads or tusk sockets of elephants. See also gajamukta and gajamuthu.
endoscope method: Method of testing whether a pearl is natural or cultured; conducted by inserting a hollow needle into the drill hole of a pearl and examining the behavior of a ray of light projected through the hole and reflected from a small mirror at the end of the needle. The light reflects and bends with the concentric layers of a natural pearl and shines out the drill hole. The light enters the roughly parallel layers of a cultured pearl’s bead and travels through them to the surface.
epithelial cells: Cells on the shell side of a mollusk’s mantle tissue that produce mother of pearl and nacre.
epithelial graft tissue: Piece of mantle tissue from a donor mollusk implanted with a mother-of-pearl bead in the gonad or other body part of a host mollusk to produce a cultured pearl; or implanted with or without a bead in the mantle of a host mollusk to produce a cultured pearl.
essence d’orient: Paste made of several ingredients including scales from the undersides of certain fish. It is applied as a coating to glass beads to make imitation pearls; also called pearly essence.
exotic freshwater pearls: Cultured freshwater pearls that exhibit uncommon colors like green, gold, blue or orange.
F
faceted cultured pearl: Pearl carved to create rhombic or triangular surface shapes that produce a sparkling optical effect when the wearer moves.
fancy colors: Most often associated with cultured freshwater pearls, consist of unusual colors like intense pink, orange or plum.
fancy shapes: Most often associated with cultured freshwater pearls, consist of unusual shapes like bars, crosses, letters, dragons and triangles.
faux pearl: Any imitation pearl.
feather pearl: Cultured pearl gown in the (fancy) shape of a bird feather.
feeding pearl: Legend in India that describes feeding a pearl to a rooster to let its digestive acids restore the original beauty of an old pearl.
first-generation cultured pearl: Freshwater or saltwater cultured pearl whose growth is started by implanting a tissue piece, or a bead nucleus and tissue piece, in a host mollusk that has not grown a pearl before.
fitaam: Wooden nose clamp used by natural pearl divers in the 19th century.
fjeris: Folk songs developed and sung by the pearl divers while on pearling ships in the 19th century.
flame structure: Optical effect commonly associated with conch pearls; produced by aragonite crystals arranged in two directions that are often intertwined.
floor system: Method of pearl farming used in Australia where mollusks are placed in baskets attached to posts or fences and left on the seabed.
flower pearl: Cultured freshwater pearl grown in the (fancy) shape of a flower.
folded crown mussel: Common name for Cristaria plicata, a freshwater mussel that’s also called the cockscomb mussel.
fossil pearl: Pearl that has fossilized and usually dates back to the Pliocene and Miocene periods.
free suspension: Method of pearl farming where mollusks are suspended in wire or nylon panels.
French dye method: Method of dyeing natural and cultured pearls using an organic coloring agent; originated in France.
French river pearl: Imitation pearl made from the hinge of Pinctada shells.
Freshadama pearls: Trade name for freshwater pearl strands composed of loose, gem-grade freshwater pearls exhibiting orient.
freshwater pearl: Pearl grown in a mussel in a non-saline environment.
fuhyu pearl: Chinese name for natural or cultured abalone pearl found or grown in Haliotis discus.
Fujita, Masao: Known as the father of the cultured freshwater pearl industry, Fujita was the first to culture whole freshwater pearls in Lake Biwa, Japan.
Fujita rose pearl: Freshwater pearl from Lake Biwa first developed and marketed by Dr. Masao Fujita in 1930. The pearls were produced by implanting a drilled mother-of-pearl bead and a donor-mussel tissue piece in the host mussel’s soft body.
funado: Kind of ama (Japanese pearl diver) who worked with a partner and a boat.
G
gajamukta: So-called pearl said to come from the heads or tusk sockets of elephants; also called elephant pearl.
gajamuthu: Same as gajamukta and elephant pearl.
ganglia or ganglions, plural, ganglion, singular: Groups of nerve cells that make up the nervous system of a bivalve mollusk.
gastropod: Univalve mollusk, including land and sea snails, with a head and eyes.
gamma ray irradiation: Method of darkening freshwater pearls and the mother-of-pearl core of bead-nucleated saltwater pearls by altering the trace element manganese.
gem quality: Perfectly clean pearl exhibiting fine color and luster.
giant clam: Tridacna gigas, a non-nacreous natural pearl producer that is listed as a threatened species in Appendix II of the international CITES treaty.
giant clam nucleus: Bead nucleus formed from the shell of a giant clam. It is a violation of the international CITES treaty for any signatory nation to import or permit the use of wild giant clams for any purpose.
GIE Perles de Tahiti: (GIE = Groupement d’Interet Economique) Government organization responsible for regulating the Tahiti cultured pearl industry and promoting its products.
GIE Poe Rava Nui: Cooperative of Tahitian pearl producers and wholesalers.
GIA: Gemological Institute of America, nonprofit school and gemological laboratory founded in 1931; headquarters are in Carlsbad, California.
GIA pearl grading system: Grading system for cultured pearls; developed by GIA in the late 1990s.
glacier pearl: Imitation abalone pearl made from abalone shell.
glass nucleus: Bead used to produce imitation pearls like the Majorica brand.
glochidia: Freshwater mussel larvae.
gold-lip mollusk: Pinctada maxima mollusk used to produce of natural-color gold South Sea pearls. The outer edges of the shell interior are gold in color.
gonad: In saltwater bivalve pearl-producing mollusks, the reproductive organ where a bead nucleus or nuclei and donor-mollusk tissue piece or pieces are implanted to produce cultured pearls.
graduated strand: Strand of pearls with 3 mm or more gradation from the ends to the middle, with the largest pearl as the center.
graft tissue: Donor-mollusk mantle tissue piece implanted with or without a bead nucleus in a host mollusk to produce a cultured pearl.
graft: To insert a piece of graft tissue with or without a bead nucleus in a host mollusk to induce it to produce of a cultured pearl.
grain: Unit of weight associated with natural pearls. One grain equals 0.25 carat.
greffon: Term used in French Polynesia to describe the grafting process.
H
H-grade pearl: Letter grade assigned to a high-grade pearl by Japan’s Pearl Inspection Office from 1952 to 1999.
half-drilled pearl: Pearl drilled to 2/3 or 3/4 of its diameter for setting in pearl jewelry.
half-light pearl: One of four Saxony quality factors used to describe natural German river pearls. See also: light pearl (highest quality), and sand and rotten pearl (lowest qualities).
half-round nucleus: Nucleus used to produce cultured blister pearls. A half-round nucleus has a domed side and a flat side; the latter is attached to the host’s shell.
Haliotis: Large genus of gastropods commonly known as abalone.
hamadera auction: First cultured akoya pearl auction, January 8, 1920, Osaka, Japan. Two kilograms of Mikimoto’s pearls were sold at the auction.
hama-age: Newly harvested cultured akoya pearls in Japan.
hama-age auctions: Annual auctions of newly harvested cultured akoya pearls in Japan.
hammer pearl: Brownish-black natural pearl produced by the hammer shell, Malleus malleus.
hanadama: Highest quality portion of a cultured akoya pearl harvest.
hanadama certification: Cultured akoya pearl certificate issued by the Pearl Science Laboratory of Japan indicating cultured akoya pearls that have the highest ratings in all quality attributes.
hankei: Japanese name for a cultured blister pearl.
hardness: Pearls range from 3.5 to 4.5 on the Mohs hardness scale.
harvest: Removing cultured pearls from mollusks on a pearl farm.
heat treatment: Applying heat to a natural or cultured pearl to improve its luster.
Heath pearls: Natural pearls from the Heath region of Scandinavia; popular in the latter half of the 19th century.
Hepu pearls: Natural pearls collected from Hepu and Behai in Guangxi Province, China, as early as the Han dynasty (206-220 AD).
hinge pearl: Natural pearl found near the hinge of a bivalve mollusk, typically of elongated, irregular shape.
hollow pearl: Natural or cultured pearl with a large, hollow cavity.
Hope Pearl: Natural marine blister pearl weighing 1,816 grains (454 carats), probably from Pinctada margaritifera.
hue: First impression of a pearl’s color.
hybrid mussel: Pearl mussel created by crossbreeding two species.
hypostracum: Mother-of-pearl layer of a pearl-bearing bivalve mollusk shell, the shell layer adjacent to the mantle.
Hyriopsis genus: Unionidae family mussels native to Southeast and East Asia. Pearl-producing species of the genus occur in China and Japan.
Hyriopsis cumingi: Triangle shell mussel native to China, used extensively in cultured freshwater pearl production.
Hyriopsis schlegeli: Biwa pearly mussel native to Japan, used to produce tissue-cultured freshwater pearls in Lake Biwa. Also used in China since the mid-1990s as a pure species and as a hybrid with Hyriopsis cumingi.
I
I-pearls: Imitation pearls from Izumi, Japan.
icon pearl: Cultured blister pearl produced in the shape of an iconic object by using a nucleus of that shape.
IGI grading system: Cultured pearl grading system developed by the International Gemological Institute in New York in 1993. The system uses 22 reference strands to grade color, luster, nacre, shape and surface according to point values ranging from 1 (lowest) to 30 (highest).
ikecho-gai: Japanese name for the Biwa pearly mussel, Hyriosis schlegeli. Translated to English, ikecho-gai is pond butterfly shell.
image pearl: An image pearl, similar to an icon pearl, is a cultured blister pearl in the shape of an image like a Buddha or a dragon; first cultured in Cristaria plicata (cockscomb) mussels in China in the late 1200s.
imitation pearl: Any material that simulates the appearance of a cultured or natural pearl but does not possess either’s physical properties.
immature pearl: Natural pearl that shows discoloration from a conchiolin core or darkened conchiolin rings.
imperial golds: South Sea pearls from the gold-lip pearl mollusk (Pinctada maxima) that exhibit deep gold color saturation.
Incomparable, The: See Peregrina, La.
indicator pearl: Small South Sea pearl (also known as a baby pearl) harvested from Pinctada maxima after six to eight months so a larger nucleus can be inserted in the existing pearl sac. The pearls are generally small and have thin nacre. Indonesia is the primary producer.
infrared spectroscopy: Method of determining the agents used to change the color of a cultured or natural pearl. It is also used to determine the chemical composition of imitation pearls.
interference: Interference of light by nacre creates the iridescent play of color on the surface of a pearl. Refraction, diffraction and/or thin-film interference occur as light penetrates extremely thin nacre layers.
iridescence: Play of color over the surface of a pearl as interference divides white light into its component colors.
irradiation: Exposing a cultured pearl to gamma rays darkens the nacre of a freshwater pearl or the freshwater mussel bead within a cultured saltwater pearl by affecting the manganese each contains.
Ise pearl: Natural white pearl from Ago Bay, Japan. Cultured akoya pearls eclipsed Ise pearls.
J
Japan Black Pearl Promotion Association: Founded in October 1993, the association promotes cultured pearls from French Polynesia in Japan.
Japanese lingah: Popular name for the Pinctada fucata martensi mollusk.
Japanese pearl mollusk: Akoya pearl mollusk.
Jewelmer: Philippine producer and wholesaler of South Sea pearls, primarily those produced by the gold-lip Pinctada maxima pearl mollusk.
jin: Historical weight unit used to valuate natural pearls in China during the Ming dynasty (1368-1644 AD). One jin equals 500 grams.
jiwan: Historical Persian quality factor describing round, pink natural pearls with high luster.
John Guise School of Pearl Culture: Founded in New Guinea by Australian C. Denis George. The school trained villagers in pearl culture.
Jomon Pearl: The world’s oldest known pearl, believed to be more than 5,500 years old.
JPEA (Japan Pearl Exporters’ Association): Founded in 1954, disbanded in 1999 and recently reestablished (with little support), the JPEA is an association of pearl farmers and dealers that works to promote cultured pearls and to ensure that low-grade pearls are not exported from Japan.
JVC (Jewelers Vigilance Committee): US-based nonprofit group that works to ensure legal compliance and ethical standards within the jewelry industry.
K
karasu-gai: Japanese term for the Cristaria plicata (cockscomb) freshwater pearl mussel.
kago: Japanese term for pearl mollusk baskets suspended from longline systems.
kan: Historical Japanese weight unit used to valuate pearls. One kan equals 1,000 momme (see), 3.75 kilograms and 8.26 pounds.
kangaroo basket: Underwater basket in which pearl mollusks are stored for a short period after the grafting process. The baskets have individual pockets meant to catch expelled nuclei.
koao: Coral platforms on which pearl farms are built on Manihiki atoll in the Cook Islands.
kashra: Historical Persian quality factor describing blister pearls.
Kasumigaura cultured pearl: Cultured pearl grown in Japan’s Lake Kasumigaura in a hybrid freshwater pearl mussel (Hyriopsis schlegeli/Hyriopsis cumingi).
keshi: Japanese term for “poppyseed.” Originally, the term referred to a small natural or cultured pearl.
keshi cultured pearl: Trade term for a saltwater pearl produced as an accidental byproduct of the pearl culturing process.
khardil: Historical Persian quality factor describing black pearls.
Komatsu flower pearl: Original faceted cultured akoya pearl developed by Japan’s Komatsu Diamond Industry Company in 1992.
koshimono: Japanese term for cultured akoya pearls grown for two years.
Kunz, George Frederick: With Charles H. Stevenson, author of The Book of the Pearl, published in 1908.
Kuri Bay: Site of the first successful Australian South Sea pearl farm, founded in 1956 in remote Western Australia. The site was named for Tokuichi Kuribayashi, president of Japan’s Nippo Pearl Company, which owned the Arafura Pearling Fleet.
Kuta pearl: Cultured blister pearl grown in Pinctada maxima off the island of Bali. A section of sea urchin is embedded in the resin when the blister is filled to form a mabe pearl.
L
L-grade: Letter grade assigned to low-grade pearls by Japan’s Pearl Inspection Offices from 1952 to 1998.
La Paz pearls: Natural pearls from Central America.
lacquer coating: Temporary coating applied to some imitation and cultured pearls to enhance their color and luster.
Lake Biwa: Located northeast of Kyoto, Lake Biwa is Japan’s largest freshwater lake and site of that country’s first freshwater pearl culture operations, headed by Dr. Masao Fujita.
Lake Kasumigaura: Located northeast of Tokyo, Lake Kasumigaura is Japan’s second largest freshwater lake and origin of Kasumigaura (Kasumi, Kasumiga) pearls.
Lamprotula leai: Freshwater mussel native to China. The mussel is a source of bead nuclei but is not used in pearl culture.
lantern baskets: Baskets used to hold young mollusks when suspended from lines during saltwater pearl culture. Method is most often used for akoya mollusks for a short period after they are bred in hatcheries.
laser treatment: Supposed method of modifying a cultured pearl’s color. It is often claimed but does not actually exist.
Latendresse, John: (July 26th, 1925–July 23, 2000) A pioneer of freshwater pearl culture in the United States.
lead nuclei: Used by Mikimoto in his early attempts at akoya pearl culture. The attempts failed.
liang: Historical weight unit used to valuate pearls in China. One liang equals 1/10 or 1/16 jin. One jin equals 500 grams.
lianzhu: Historical Chinese quality factor that described the finest quality natural pearls.
ligament pearl: Defunct trade term once used to describe a natural pearl formed within the mantle isthmus, just below the ligament.
light pearl: One of four Saxony quality levels used to describe natural German river pearls. A light pearl was of the finest quality. See also: half-light pearl (high quality), sand and rotten pearl (the lowest qualities).
Linné, Carl von: (May 13, 1707–January 10, 1778) Also known as Carolus Linnaeus. In 1758 he originated the binomial system of zoological taxonomy that has been used since. He was the first person to culture whole pearls.
lion’s paw pearls: Non-nacreous scallop pearls that exhibit white, pink, violet and/or orange colors.
Little Willie: Discovered by Bill Abernethy in Scotland in 1967. This natural freshwater pearl is round, meaures 11.6 mm and weighs 34 grains (8.5 carats). Same as Abernethy Pearl.
longline systems: Horizontal lines stretched between buoys and anchored to the bottom at both ends. Chaplets (vertical lines) with baskets or net panels of nucleated mollusks are suspended underwater from the longlines.
luli: Ancient Roman imitation pearls made from glass with a coating of silver and another layer of glass.
luster: Quantity and quality of light reflected from the surface or just under the surface of a natural or cultured pearl.
M
mabe: Originally, the Japanese trade term for an assembled blister pearl grown in Pteria penguin. In Japanese, that mollusk’s name is mabe-gai, hence the pearl’s name. Today, the word is used to describe any assembled blister pearl.
maeshori: Originally in Japan, a deep-cleaning process used before bleaching akoya cultured pearls. Today, "maeshori" (literally, "before treatment") retails its original meaning, but is also the name of several treatments used to enhance the luster or most Chinese freshwater, and some South Sea and akoya cultured pearls.
Magan Moshe Pearl: Natural abalone pearl weighing 349.41 carats. It was purchased by Moshe Pereg and given its name in 1989.
majhoolah: Historical Persian quality factor describing a blister pearl from which a round and better pearl might be removed by peeling.
Majorica pearl: Imitation pearl created by coating a glass nucleus with essence d’orient (see). The pearly essence is made from guanine crystals extracted from scales on the undersides of certain fish.
Manihiki Pearl Producers’ Association: Association of Pinctada margaritifera cumingi pearl producers in the Cook Islands.
mantle: Organ lining the shell of freshwater and saltwater bivalve mollusks.
mantle graft tissue: Tiny piece of tissue cut from a donor mollusk’s mantle and implanted with or without a bead nucleus in a host mollusk to produce a cultured pearl. The outer epidermis of the mantle is made up of epithelial cells that secrete nacre.
maona pearl: Samoan term for imitation pearl created from the operculum (see) of Turbo petholatus.
margarita: Greek and Latin word for pearl.
margaritifera: Genus name (capital M) applied to a group of freshwater mussels, and the species name (lowercase m, genus Pinctada) applied to the black-lip pearl mollusk.
master set: Group of pearls used for comparison to assess the quality characteristics of cultured pearls submitted for grading.
matching: Matching pearls for uniformity in a strand or piece of finished jewelry.
matinee length: Pearl necklace measuring 20 to 24 inches (50 to 60 cm).
mature pearl: Natural pearl described as being of the most beautiful water (see).
melo pearl: Natural non-nacreous pearl found in the Melo melo marine gastropod.
Mikimi: Trade name for second or third grade Majorica imitation pearls.
Mikimoto, Kokichi: (March 10, 1858 – September 21, 1954) First person to commercially produce spherical cultured pearls using the Mise-Nishikawa method of pearl culture, which that pair most likely learned from Englishman-turned-Australian William Saville-Kent.
Miyoko pearls: Imitation pearls marketed in Germany in 1983.
Mise-Nishikawa method: Method of saltwater pearl culture by which a bead nucleus and piece of donor-mollusk mantle tissue are implanted in the gonad of a host mollusk. The technique was most likely first developed by Englishman-turned-Australian William Saville-Kent.
Mise, Tatsuhei: With Tokishi Nishikawa, credited (probably erroneously) in the early 1900s with developing the method of saltwater whole pearl culture still used today.
Mitsubishi pearls: First pearls produced in Pinctada maxima by Dr. Sukeyo Fujita between 1928 and 1932 on the Malaysian Island of Sulawesi. The project was financed by Baron Iwasaki of the Mitsubishi Company.
mollusk: Any invertebrate from the phylum Mollusca.
momme: Japanese weight unit used to valuate cultured pearls. One momme equals 3.75 grams.
mother-of-pearl: Iridescent layer (principally calcium carbonate and conchiolin, see) lining the inner shell of some mollusk species. When it coats a bead to form a cultured pearl or composes a natural, tissue-cultured or keshi pearl, it’s called nacre (see).
muta’a: Historical Persian quality factor describing baroque pearls.
N
nabatee: Arabian term for sugar used to describe pearls from the Persian Gulf that had a slightly off-white, yellowish color.
nacre: Aragonite and calcite platelets bound together by conchiolin that completely compose bivalve and abalone natural pearls, keshi, tissue-cultured freshwater pearls, and the coating on the nucleus of bead-cultured and bead-and-tissue-cultured pearls.
nacreous: Composed of nacre.
nacre thickness: Measured in whole and decimal fractions of millimeters, the depth of the nacre layer on the bead nucleus of bead-cultured and bead-and-tissue-cultured pearls. Not a consideration for natural and cultured pearls composed entirely of nacre (see).
Nassau pearl: Historical term for conch pearl.
National Federation of Pearl Cultivators’ Cooperative Association (Zen Shin Ren): Japanese association that organizes hama-age auctions.
National Pearl Research Laboratory: Established in 1952 in Mie Prefecture, Japan, with the intention of improving pearl culture technologies.
natural pearl: Organic gem created in a mollusk without human intervention.
Nautilus pearl: Natural pearl from Nautilus pompilius, extremely rare. Osmenda imitation pearls are often incorrectly called nautilus pearls.
nimro: Historical Persian quality factor describing blister pearls.
Nishikawa, Tokishi: Credited with Tatsuhei Mise (probably erroneously), with discovering the bead-and-tissue method of whole pearl culture.
non-beaded cultured pearl: Cultured pearl grown without a bead nucleus.
non-nacreous pearl: Natural pearl lacking a nacreous surface layer.
non-nucleated cultured pearl: Cultured pearl grown without a bead nucleus.
nucleus: Bead implanted in a host mollusk, most often with a tissue piece, to become the core of a cultured pearl.
nuggets: Semi-round pearls that resemble gold nuggets.
O
Occidental pearls: Historical term used to describe natural pearls from Mexico, dates to the 16th century but fell from usage after 1930.
oil pearls: Imitation pearls worked from the columella (see) of the Trochus and Turbo snails.
oiling: Process of soaking a natural or cultured pearl in warm oil to diminish the visibility of cracks.
opera necklace: Pearl necklace measuring 28 to 35 inches (70-90 cm).
operculum: Shell-like cover that closes the opening of some marine gastropod shells.
Orama Pearls: Trade name for cultured blister pearls sold to tourists on Rarotonga in the Cook Islands.
organic dyes: Used to change the color of natural and cultured pearls.
orient: Optical phenomenon that produces iridescent colors on the surface of some natural and cultured pearls. One or more of these factors creates orient: reflection, refraction, diffraction, and thin-film interference.
Oriental pearls: Historical commercial term for natural marine pearls from the Persian Gulf and the Red Sea.
Osmena pearl: Also called Osmend or Osmenda pearl. Imitation pearl worked from the inner coil of the Nautilus pompilius shell.
ostracum: Central, prismatic layer of a bivalve mollusk shell.
ounce pearls: Historical trade term describing small natural pearls offered in lots.
oval: Natural or cultured pearl in an oval or egg shape.
overtone: Secondary color on the surface of a natural or cultured pearl. It is created by nacre layers interfering with white light and splitting it into its component colors.
oyster: Common name correctly applied to some bivalve mollusks and incorrectly to others. No bivalve mollusk that produces nacreous natural or cultured pearls is a true oyster.
oyster pearls: Chalk-like natural pearls produced by edible oysters (Family Ostreidae), low in commercial value.
P
PAPPE: Philippine Association of Pearl Producers and Exporters.
paraffin: Wax often used to fill the cavity of cultured and imitation blister pearls.
parasite theory: Natural pearl growth theory suggesting that parasitic invasion of a mollusk’s shell, typically by a boring worm, catalyzes natural pearl production. Postulated in the mid-19th century, it was the first theory that countered the legend that a grain of sand stimulated natural pearl production.
Paspaley, Nicholas: Founder of Australia’s largest South Sea cultured pearl production and marketing company.
peacock: Color most often associated with pearls produced by the black-lip (Pinctada margaritifera) mollusk. It’s a dark green gray to blue gray with rosé to purple overtones.
pear: Drop pearl shaped like a pear.
pearl: Nacreous or non-nacreous calcareous concretion formed as a progressive secretion naturally and circumstantially within a mollusk.
Pearl Business Act (Shinju Yoshoku Jigyouho): Law passed in 1952 to regulate the cultured pearl industry in Japan.
pearl factory: Business establishment where pearls are processed, often treated, drilled, matched and often strung or paired before sale.
Pearl Federation of the Cook Islands: Association responsible for technical support to Cook Islands pearl farmers and the development of the cultured pearl industry there.
Pearl of Allah: Natural pearl from the giant clam (Tridacna gigas), it is the world’s largest non-nacreous calcareous concretion. It measures 23 cm by 14 cm by 14 cm and weighs 6.37 kilograms. The pearl was found off Brooke’s Point, Palawan Island, in the Philippines on May 7, 1934.
Pearl of Asia: Natural pearl believed to be from the South Sea pearl mollusk (Pinctada maxima) and to be more than 300 years old. It measures 76 mm by 50 mm by 28 mm and weighs 600 carats.
Pearl of Lao Tse: See Pearl of Allah.
pearl eyes: Historical trade term that likely refers to perfectly round pearls.
Pearl of Kuwait: White, drop-shape natural pearl weighing 257.41 grains and measuring 41.27 mm by 19.05 mm.
Pearl of Queens: Pink, 15-mm freshwater pearl weighing 93 grains.
pearl powder: Ground nacre, often used in medicines and cosmetics.
pearl sac: Grown from epithelial cells to envelop an intruder or a bead nucleus, it deposits nacre and forms a natural or cultured pearl.
pearl sieves: Used to sort cultured pearls by size.
peeling: Removing the outer nacre layers of a cultured pearl in the hope of improving its quality.
Pelegrina, La: Two natural pearls of the same name; the first is a perfectly round pearl with brilliant water and weighing 111.5 grains. The second is a drop-shape natural pearl weighing 133.2 grains.
Peregrina, La: Natural drop-shape pearl weighing 203.84 grains taken from a slave on an island in the Gulf of Panama in 1513 by the Spanish conqueror Vasco Nunez de Balboa.
periostracum: Outer layer of a bivalve mollusk shell, formed of conchiolin.
Perles de Tahiti: See GIE Perles de Tahiti.
petals: Freshwater cultured pearls in the shape of leaves or flower petals.
pin pearl: Natural nacreous or non-nacreous pearl produced in mollusks from the Pinna or Atrina genus; often mistakenly called pen pearl.
Pinctada: Mollusk genus in the family Pteriidae. It’s the most important genus in saltwater cultured pearl production.
Pinctada chemnitzi: Native to China and parts of Japan, the pure species and its hybrid with Pinctada fucata martensi are used to produce akoya cultured pearls in those countries.
Pinctada fucata martensi: Historically, the Japanese akoya pearl mollusk. The species is now used there and in China to produce akoya cultured pearls. It is often cross-bred with Pinctada chemnitzi.
Pinctada imbricata: Some researchers say this species name encompasses every mollusk species called "akoya" regardless of geography. As is true elsewhere in taxonomy, other researchers disagree.
Pinctada margaritifera: The black-lip pearl mollusk; the variety Pinctada margaritifera cumingi is used to produce Tahitian and Cook Islands cultured pearls.
Pinctada martensi: Synonym for Pinctada fucata martensi.
Pinctada maxima: The silver-lip or gold-lip pearl mollusk; used to produce South Sea cultured pearls.
Pinctada mazatlanica: Evolved from Pinctada margaritifera, it is native to the Gulf of California (Sea of Cortez) and the Mexican and Central American Pacific Ocean.
Pinna pearl: Natural nacreous or non-nacreous pearl produced in mollusks from the Pinna or Atrina genus; often mistakenly called pen pearl.
pipi pearl: Small, yellowish natural pearl produced by Pinctada maculata.
poe pipi: Polynesian and Maori term for a pearl from the Pinctada maculata mollusk.
poe rava: Tahitian-language term for dark iridescent pearl. Some use the term to describe peacock-color pearls or deeply black pearls.
Poe Rava Nui: See GIE Poe Rava Nui.
polishing: Enhances the luster of natural or cultured pearls.
polymer coating: Synthetic silicone polymer film often applied to lower-quality cultured pearls to enhance their luster.
poonak: Historical Indian weight unit used to valuate pearls, equal to 0.91 carats. It’s also called rati.
potato: Oblong pearl shaped like a potato.
princess necklace: Pearl necklace measuring 17 to 19 inches (43 to 48 cm).
Pteria penguin: Mollusk originally used to produce assembled cultured blister pearls. In Japanese, its name is mabe-gai.
Pteria sterna: Rainbow-lip mollusk used to culture pearls in the Gulf of California (Sea of Cortez).
Q
quahog: Saltwater bivalve mollusk (Mercenaria mercenaria) also known as the cherrystone clam.
quahog pearl: Small, often violet natural pearl with a porcelaneous surface produced by the quahog mollusk.
Quality Assurance Tag: Introduced by JPEA in 1999 as a voluntary quality-control system, the tag is attached to temporary cultured pearl strands before export to indicate they have met minimum quality standards.
quality factors: Characteristics of natural or cultured pearls used to establish their value.
queen conch: Gastropod (Strombus gigas) that produces natural non-nacreous pearls known as conch pearls.
queen’s necklace: Pearl necklace measuring 31.5 inches (80 cm).
R
radial structure: Calcite or aragonite crystals of a pearl’s prismatic layer are arranged in a pattern so they radiate like rays of sunlight from a central core. In a cross-section view, the crystals stand on end rather than lie flat as in the nacre layer.
rainbow pearl: From Pinctada mazatlanica but exhibits colors like pearls from the black-lip mollusk (Pinctada margaritifera).
rakes: Used to collect wild freshwater mussels by dragging across the beds of rivers, lakes and ponds.
Raman spectroscopy: Laboratory method of testing cultured pearls for presence of silver nitrate, which is a pearl dyeing agent.
rati: Historical Indian weight unit used to valuate pearls, equal to 0.91 carats. Also called a poonak.
red tide: Profuse hyperproduction of algae, called an algal bloom. It weakens or kills pearl-bearing mollusks by consuming most or all of the dissolved oxygen in the water and/or poisoning them when the algae die and putrefy. It’s not a true tide, and it’s not always red.
Red Sea cultured pearl: Cultured pearl produced in the local black-lip (Pinctada margaritifera) mollusk in the Red Sea.
refractive index: Measure of the degree that light bends when it moves from one medium to another, for example, from air into nacre. The refractive index of natural and cultured pearls is 1.51 to 1.66.
Régente, La: Egg-shaped natural pearl weighing 302.68 grains (75.67 carats).
Reine des Perles, La: Round natural pearl from the French crown jewels. It weighs 110 grains (27.5 carats).
rice krispies: Chinese freshwater pearls that often have a textured surface and look like puffed rice kernels. They take their name from the American breakfast cereal Rice Krispies, called Rice Bubbles in Australia. The pearls were cultured in the cockscomb mussel (Cristaria plicata) and first appeared on the international market about 1970.
Roman pearls: Imitation pearls also known as “alabaster pearls.”
rope: Pearl strand measuring more than 45 inches (115 cm).
rotten: One of four Saxony quality factors used to describe natural German river pearls, rotten being the lowest quality. Also see: light (highest quality), half-light (high quality), and sand (low quality).
round: Perfectly round pearl, or one with diameters that don’t vary by more than 2 percent.
royal gem pearl: Imitation pearl produced from the lens of a fish eye.
S
saltwater pearl: Natural or cultured pearl produced by a saltwater mollusk.
sand pearls: One of four Saxony quality factors used to describe natural German river pearls; sand pearls are of low quality. Also see: light pearls (highest quality), half-light pearls (high quality), and rotten pearls (lowest quality).
sautoir: Pearl strand longer than 36 inches (90 cm).
Saxon pearl necklace: Necklace created from natural freshwater pearls found in the Vogtland (Germany) between 1719 to 1912.
scallop pearl: Non-nacreous pearl produced by any mollusk of the Pectinidae (scallop) family.
Scottish pearl: Natural freshwater pearl from Margaritifera margaritifera found in Scotland.
seabed system: Method of farming South Sea pearls in which Pinctada maxima mollusks are placed in baskets or panels secured to posts on the sea floor. The method is still used today in northwestern Australia but was most popular in the first decades of pearl farming there.
second-generation cultured pearl: Freshwater or saltwater cultured pearl whose growth is started either by implanting a shell bead nucleus in an existing pearl sac from which a first-generation cultured pearl was removed, or by letting the mollusk grow a beadless cultured pearl in an existing pearl sac from which a first-generation cultured pearl was removed.
second grafts: Cultured pearls grown in existing pearl sacs after the first harvest; same as second-generation cultured pearl. The term is misleading because there is no tissue graft involved.
seed pearl: Natural pearl less than 2 mm in diameter.
semi-baroque pearl: Off-round, asymmetrical pearl but not quite as irregular as a baroque pearl.
semi-round pearl: Off-round pearl having a symmetrical shape or a slight deviation of symmetry. To be semi-round, a pearl’s diameters must vary by more than 2 percent. Also called near-round.
shell pearl: Imitation pearl made from a mollusk shell.
shinju: Japanese word for pearl.
shireen: Historical Persian quality factor describing natural pearls of very high luster and excellent shape.
shiro-gai: Japanese term for white shell. It typically refers to Pinctada martensi, which has a strikingly white inner shell layer that produces very white pearls.
sijni: Historical Persian quality factor describing natural pear-shaped pearls.
silver-lip mollusk: Pinctada maxima mollusk that has silver rather than gold inner shell edges; used to culture South Sea pearls.
silver nitrate: Dye used to darken cultured pearls. The compound turns black when exposed to light.
simpatico: A term that describes the relationship, interaction between a person's skin and the differing types; colors/overtones/orient of pearl(s). A specific pearl(s) that interacts with the skin in a positive way and flatters the wearer can be said to be simpatico with that person.
sindaali: Historical Persian quality factor describing a natural, flesh-colored pearl.
sinjabaasi: Historical Persian quality factor describing natural pearls of the finest black color.
slug: Several pearls fused together so they resemble a slug.
sofri: Historical Persian quality factor describing natural pearls of a yellow color.
South Sea pearl: Natural or cultured pearl produced by the Pinctada maxima mollusk.
Southern Cross, The: Cross-shaped group of natural pearls found on the Australian west coast in 1874. A vertical line of seven pearls measuring 3.8 cm had a single pearl attached to each side so the group formed a cross. It’s now believed the arms were glued on. It was named for the celestial constellation that is visible only in the Southern Hemisphere.
spat: Saltwater mollusk larva old enough to attach itself to a fixed surface.
Strombus gigas: Queen conch.
surface: One of the quality factors considered when grading a natural or cultured pearl.
sweet water pearls: Trade term for freshwater pearls.
symmetrical pearl: Exactly the same shape on both sides of a central axis.
synthetic pearl: Artificially grown pearl.
T
Tahitian cultured pearl: Produced by a black-lip mollusk (Pinctada margaritifera) in French Polynesia.
Tahiti cultured pearl: Produced by a black-lip mollusk (Pinctada margaritifera) in French Polynesia.
Tahiti Black Pearl Promotion Association: Founded in 1994 to promote Tahitian cultured pearls in the United States.
Takara pearl: Imitation pearl made with a mother-of-pearl nucleus.
tank: Indian unit of weight equal to 72 grains or 24 ratis.
Tavernier, Jean Baptiste (1605 to 1688): Frenchman of great influence in the natural pearl trade who developed a system of grading known as “Tavernier’s Rule.”
Tavernier’s Rule: Seventeenth century valuation procedure that multiplies the size factor, or grain weight of a pearl, by itself, and then by a quality factor ranging from 0.5 to 30 that is based on shape, color, luster and surface to arrive at the value of a natural pearl.
te ufi: Term for black-lip mother of pearl used by original inhabitants of French Polynesia.
teri: Japanese term for luster.
third-generation cultured pearl: Freshwater or saltwater cultured pearl whose growth is started either by implanting a shell bead nucleus in an existing pearl sac from which a second-generation cultured pearl was removed, or by letting the mollusk grow a beadless cultured pearl in an existing pearl sac from which a second-generation cultured pearl was removed.
third graft: Cultured pearl grown in an existing pearl sac after the second harvest. The term is inaccurate because no tissue graft is involved.
three-quarter cultured pearl: Bead-and-tissue-cultured pearl, most often akoya, that is worked to remove an imperfection, leaving a flat portion of the nucleus exposed. The flat side is usually half-drilled and mounted on a post in a setting that conceals the worked side.
tinting: Dilute color dye treatment that produces a slight change in a pearl’s color, usually making it pink.
tissue-cultured pearl: Freshwater cultured pearl whose growth is started by implanting a donor-mollusk mantle-tissue piece in a host mollusk’s mantle.
tissue method: Implanting a freshwater host mussel with a donor-mussel mantle-tissue piece to start the growth of a beadless cultured pearl.
U
Unio: Genus in the Unionidae freshwater mussel family. Several species in the genus produce pearls.
underwater platform: Used in French Polynesia as a temporary care station from which mollusks are suspended after implantation of a bead nucleus and donor-mollusk tissue piece.
uroko: Japanese term for scaly spots on akoya cultured pearls.
V
Venezuelan necklace: Legendary strand of pearls owned by Spain’s Queen Isabella.
Venus pearls: Natural non-nacreous pearls from Veneridae-family saltwater mollusks that are often called Venus clams.
virgin pearl: Historical term for an undrilled or freshly harvested pearl.
Vologne pearl: Natural freshwater pearl from the French province of Lorraine, specifically from the Vologne River.
W
Wada method: Developed by Dr. Koji Wada of Japan, a method of choosing donor-mollusk mantle tissue to help determine a cultured pearl’s color.
wampums: Cylindrical beads made from quahog shells by native Americans and used as jewelry or money.
Wan, Robert: Founder of the Tahiti Perles Company, which became the largest producer of Tahitian cultured pearls.
warm hues: Colors from purplish red to orangey yellow to greenish yellow, as defined by the GIA color-reference chart.
water: Historical trade term used to describe the translucency of a pearl.
wax pearls: Imitation pearls made from hollow glass spheres filled with wax, popular during the early 20th century.
waxing: Application of wax to a pearl’s surface to enhance its luster.
wings: Natural pearls shaped like wings.
Winston Pearl, The: Natural freshwater pearl measuring 44 mm in diameter and weighing 601.24 grains purchased by New York jeweler Harry Winston in 1987. It’s believed to be the largest freshwater pearl in the world.
wooden wedge: Used to separate the valves of a host pearl mollusk so a donor-mollusk tissue piece or bead and tissue piece can be implanted.
working: Removing layers of nacre from a natural or cultured pearl.
World Pearl Organization: Formed in Japan in November 1994, it engages in public relations and caters to the interests of pearl producing and consuming countries.
X
X-ray testing: Used to determine whether a pearl is natural, cultured or imitation.
Y
yakkah: Historical Persian quality factor describing natural pearls of secondary quality.
yellow grains: Nineteenth century theory of natural pearl production stating that yellow grains found in some freshwater pearls were from shell-production reserve material. This organic material made its way into the mantle and catalyzed pearl growth.
yoyo: Japanese term for a host mollusk’s 45-day convalescence period after implantation of a bead nucleus and donor-mollusk tissue piece.
Z
zebra mussel: Predatory mussel that has done significant damage to freshwater mussel stocks in streams and rivers principally north of the Ohio River in the eastern United States.
zuchtperlen: German term for cultured pearls.
|
