Glossary of Pearl Terms H

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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). Also see: light pearls (highest quality), sand (low quality), and rotten pearls (lowest quality).

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.

Hank: Term for a grouping of temporary pearl strands typically tied in bundles of five or ten.

Hankei: Japanese name for a cultured blister pearl. See Mabe 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 or Pinctada mazatlanica. Once owned by 19th Century Gem collector Henry Phillip Hope.

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.
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