Coral is an organic gem, calcium carbonate with a trace of carotene, deposited by tiny sea creatures living in the depths of warm seas in huge colonies. It grows in branches that look like underwater trees. Most coral used in jewelry is found in the Mediterranean Sea or in the Pacific off Japan and Taiwan. Precious coral, or red coral, is the common name given to Corallium rubrum and several related species of this marine coral. The distinguishing characteristic of precious corals is their durable and intensely colored red or pink skeleton, which is used for making jewelry. The hard skeleton of red coral branches is naturally matte, but can be polished to a glassy shine. It exhibits a range from pale pink to reddish pink to vivid reds colors. The word 'Coral' is also many times used to name such colors.
When you say the word coral, most people think of the coral reefs in the South Pacific, like the Great Barrier Reef off Australia. However, these coral reefs are formed by a different species than the coral traditionally used in jewelry.
Thanks to AGTA, Coral Musuem and others for information on this new coral.