• Glossary of Pearl Terms O

    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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    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.