Red coral is the most valuable form of coral. The deeper the red, the more it is prized. Skeletons of coral vary in color; from bright to dark red, to slightly orange-red, to pink, black, blue, and white. Each variety of coral has a different amount of translucency. Red, pink, white, and blue (also known as Akori) varieties of coral consist of a substance similar to that of pearls, called calcium carbonate
. Akori, or blue coral, is mostly used to make beads. Black coral (also known as Akabar) and golden coral are made out of a mineral called Conchiolin
, an organic hornlike substance. Coral is relatively soft, rating only a 3 on the hardness scale
, which makes it extremely easy to carve. In general, coral is dull at first, but when polished, it has a lovely vitreous
luster. Coral is sensitive to acids and heat however, so its shine may fade with time.