Like Pearls, Corals help make up the very small list of organic
jewelry materials. Also, like pearls, Corals consist of more
than 90% calcium carbonate. The corals used in bead and jewelry
making are not the protected coral species of the fragile coral
reefs, but the more common and hearty species such as corallium
japonicum or corallium rubrum. Coral is sensitive to heat,
direct sunlight and cosmetics. Currently the International
Commission of Colored Gemstones (CIBJO) recognizes only five
organic (once living material) gemstones: Ammolite, amber,
pearl, jet, and coral.