2 PIECE BLACK OPAL STONES 0.70 CT
Black Opal is a Solid form of Opal. It has a manganese oxide base as the host structure. The level of manganese is indicated by a index level from N1 being the darkest to N9 the lightest. Black Opal is considered to be the most rare of all Opal types and is mined in Lightning Ridge, New South Wales.