Open Oval Sapphire & Diamond Ring in 18k White GoldOpen Oval Sapphire Diamond Ring in 18k White Gold. This interesting cocktail ring features a . 21 carat oval cut sapphire and . 09 carats of round brilliant cut diamonds. Set in 18 karat white gold the open shank separates the oval with a diamond halo and a single bezel set diamond on the other side. A very elegant asymmetrical design that would look great by itself or even with a stack of other rings!