O

opera necklace

pearl necklace measuring 28 to 35 inches (70-90 cm).

orient

optical phenomenon that produces iridescent colors on the surface of some natural and cultured pearls

ostracum

central, prismatic layer of a bivalve mollusk shell

oval

natural or cultured pearls in an oval or egg shape

overtone

secondary color on the surface of a natural or cultured pearl created by nacre layers interfering with white light and splitting it into its component colors