Coral is among the most ancient of gem materials, used for adornment since prehistoric times. The most valuable colors of coral are red, black, and pink, which is known as angel skin coral. Coral is much softer than other gem materials. Good quality coral has an even color and has no fissures, spots, bands or cavities. Since genuine untreated coral is rare, it is valuable.

Coral is commonly enhanced to improve its color and durability. White coral is bleached. Pink coral is permeated with a colorless wax and orange coral is stabilized with plastic. Black coral is sometimes bleached to create gold coral. Occasionally, red coral is dyed to deepen or uniform its color. All commonly used forms of coral enhancement are stable.

Coral has been used for decorative purposes and esteemed as a protective stone since time immemorial. Even today, red corals are still worn as a talisman to protect the wearer against evil spirits in many cultures. Modern gemstone therapists too highly esteem its positive effects. Coral, it is said, relieves tension and fear and promotes positive forms of social life.