Coral

Precious coral or red coral is the common name given to Corallium rubrum. The hard skeleton of red coral branches is made up of mostly calcium carbonate and is durable and intensely colored. Coral can be polished to a glassy shine. Usually, deep water corals have light color and shallow water corals have deep color. Coral jewelry has been found in ancient Egyptian and prehistoric European burials and continues to be made to the present day. Due to its softness and opacity, coral is usually cut as a cabochon or used to make beads.

Hardness: 3.5