Coral is the accumulated exudation of tiny marine animals. These animals called "coral polyps," live in huge colonies and exude a deposit of calcium carbonate, the mineral calcite, to form a protective -1 coral colony always grows perpendicular to the surface of attachment. The calcium carbonate accretion formed by the polyps is the material we know as coral.

There are many varieties and colors of coral. White coral is the mo,' common; other colors include pink, orange-pink, orange, blue, red(: ("precious coral"), and black ("king's coral"). Coral occurs throughout the world in warm climates and tropical waters having a temperature above 68°E. The most important sources are the Mediterranean Sea especially along the coasts of Algeria, Morocco, Tunisia, Sardinia, and Italy. Coral usually grows in shallow water, but some varieties form a depths of 1,000 feet. The structure of coral is very distinctive: , branched, tree-like shape. Individual branches may show a fine scale striping or banding. The only common imitations are wood, wax, and celluloid, but these can usually be distinguished on the basis of hardness ¬and microscopic examination.

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Gem quality coral is uniform in color and dense enough to take , high polish. The value of any particular color is a matter of local fashion but the deep-red variety, sometimes called-"ox-blood coral," general I.