Precious Coral Buying and the Four Cs

The IGS coral value listing has price guidelines for light pink, deep pink, and red coral cabochons. “Precious coral” refers to the material used to make jewelry and art objects.

Color

Red to pink hues of calcareous precious coral hold the most value. (These primarily consist of calcite). Most notably, Corallium rubrum is traditionally harvested in the Mediterranean Sea. Since this area has produced coral since ancient times, the color range in these organisms sets the standard for precious corals. These gems exhibit hues of “ox blood” red to light, peach-pink “angel skin.”

However, prevalent orange secondary hues will reduce prices somewhat. Red-hued corals are the most valuable. Due to increased demand from China, the value of these gems is rising.

Conchiolin corals (made primarily of conchiolin, an organic substance that’s also a component of pearls) grow in concentric circles, like tree rings. These can show brown, black, golden, or, rarely, blue colors. Although golden hues are usually the result of bleaching black coral, some natural golden coral exists.

Clarity

Most corals are opaque. However, Corallium japonicum, harvested off the coast of Japan, can be translucent. Translucence gives this…