Ross-Simons - Opal and .18 ct. t. w. Diamond Ring in 14kt Yellow Gold. Size 7. This ring exudes an utterly angelic presence. It features a stunning 8mm round opal cabochon, whose pale-toned iridescence is divinely lit by a surrounding halo of .18 ct. t. w. round brilliant-cut diamonds. Crafted in 14kt yellow gold. 3/8" wide. Diamond and opal ring. Opal birthstones are the perfect gift for October birthdays.