Glossary of Pearl Terms 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.