Cocktail Ring Modern 2.53 Cabochon Cut Opal & Diamonds in PlatinumOpals always feel magical and the stunning one is this ring is no exception. This cocktail ring is a Modern piece with a 2. 53 carat cabochon opal surrounded by a halo of diamonds. The opal has a wonderful play of color so you can see little rainbows dancing around inside of it as your hand moves. The diamonds are also exceptional in quality, they are F color and VS2 clarity. This remarkable ring is made with bright, white platinum.