5.5 - 6.5 on the Mohs scale.

Australia, former Czechoslovakia, U.S., Brazil, Mexico and southern Africa. Opal and tourmaline are the birthstones of the month of October.

Dark, iridescent, and opalescent with a wide range of internal colors.

Opal is rarely impregnated with colorless oil, wax and resins.

More information on gemstone enhancements.

Black Opal is a member of the Opal gemstone family.