Art Deco black opal and diamond ring. Set with a marquise shaped cabochon natural black opal in an open back claw setting with an approximate weight of 3.53 carats, encompassed by thirty round old cut diamonds in open back grain settings with a combined weight of 1.10 carats, and flanked by six baguette cut diamonds in open back rubover settings with a combined weight of 0.30 carats. The total approximate diamond weight is 1.40 carats, to a geometric cluster with a finely pierced gallery with leaf motifs and intricate backholing, the gently sloping shoulders flow through to a solid flat shank. Marked platinum, numbered '2496', circa 1935.

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.