Coral is made up of the skeletal remains of marine animals called coral polyps. These tiny creatures live in colonies which form branching structures as they grow, eventually forming coral reefs and atolls. The surface of these coral "branches" has a distinctive patterning made by the original skeleton - either striped or like wood grain. Most corals - red. Pink, white, and blue varieties - are made of calcium carbonate: black and golden corals are made of a horn-like substance called conch Olin. Red coral is the most valuable, and has been used in jeweler for thousands of years. Dull at first, all coral has a vitreous luster when polished, but is sensitive to heat and acids and may fade with wear. Coral may be imitated by porcelain, stained bone, glass, plastic, or rubber and gypsum mixtures.

Most precious coral is found in warm waters. Japanese coral is red, pink, or white. Red and pink coral is also found on the Mediterranean and African coasts, the Red Sea, and the waters off Malaysia and Japan. Black and golden coral is found off the coasts of the West Indies. Australia and the Pacific islands.

Coral has been associated with the protection of children, and parents may still give a gift of Coral to their young children.