Art Deco black opal and diamond ring. Set to centre with an oval cabochon natural black opal in an open back rubover setting with an approximate weight of 2.75 carats, further decorated with thirty round eight-cut diamonds in open back grain settings with a combined approximate weight of 0.60 carats, to an impressive flank solitaire design featuring polished edges, a decorative gallery with chenier motifs, and fancy shape open backholing, leading to raised stepped shoulders, and flowing through to a solid shank. Tested platinum, circa 1920.

Black opals were formed approximately 60 million years ago when silica rich water was carried into cracks and voids within the earth. As the water evaporated, it left behind a silica deposit, which has created the beautiful opals that we know today.

The colours visible in the play-of-colour of an opal depends on the structure of the gem, and depending on which angle the light hits the opal, it is diffracted differently due to the complexity of the structure, creating this fleeting, almost mystical, effect.

Black opals are considered to be the rarest and most beautiful of the opals, and the 'play of colour' contrasts beautifully against a dark body colour.

This ring is in excellent condition.