Here is a list of pearl terms that might help you better understand this site and the discussions within the community forum. It is compiled from multiple sources and we believe it to be one of the most comprehensive lists available.

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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).

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.

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.