AN OPAL AND DIAMOND RING

the large oval cabochon opal with green hues, 21mm x 14mm, claw-set within a border of twenty brilliant-cut diamonds, and flanked either side with a double row of tapering baguette-cut diamonds, on a yellow gold shank stamped "750", with milligrain-set diamond shoulders, c.1.50ct total weight (estimated), estimated ring size N