This is an authentic ROBERTO COIN 18K Rose Gold Diamond Amethyst Mother of Pearl Cocktail Ring 52 6. The ring is crafted of 18 karat rose gold and features an amethyst and mother-of-pearl cabochon surrounded by approximately .21 total carat weight of diamonds. along with a hidden synthetic ruby on the inside of the band. Follow this item for alerts. Roberto Coin is a registered trademark of Roberto Coin. FASHIONPHILE is not affiliated with Roberto Coin.