9.77 Carat Opal and Diamond Cluster Ring - 30-1-5635 - Lang Antiques. a multi-hued, rolling refulgent glow that mesmerizes - exactly what an opal should do. The enchanting gemstone, weighing just shy of 10 carats, is surrounded by half-a-carat carat of sparkling round brilliant-cut diamonds and is crafted in gleaming 18 karat yellow gold. Finger size 7. USD 3,850.