A BOULDER OPAL AND DIAMOND RING, BY GRIMA, 1974 The oval-shaped boulder opa

A BOULDER OPAL AND DIAMOND RING, BY GRIMA, 1974 The oval-shaped boulder opal within a surround of brilliant-cut diamonds, to a textured 18 carat white gold mount, diamonds approx. 0.75ct total, signed Grima, London hallmark, ring size I½