Cabochon Cut Opal and Diamond Cocktail Ring in 14KCabochon Cut Opal and Diamond Cocktail Ring in 14K. This custom made 14 karat yellow gold opal and diamond ring is set a large 5. 30 carat cabochon opal with an lovely play of color. The opal is flanked by two (2) round brilliant cut diamonds set into the shoulders on the high polish yellow gold setting. The total diamond weight is . 30 carats. The opal features flashes of color with distinct green, pink and red in the matrix.