8 Carat Sapphire Engagement Ring in Platinum & Yellow Gold8 Carat Sapphire Engagement Ring in Platinum Yellow Gold. This spectacular 8 carat sapphire is prong set in yellow gold with the rest of the ring finished in platinum. The stone makes a statement for more reasons that just its size. The sapphire is emerald cut and is set in 18 karat yellow gold, contrasting the diamonds and platinum around it. Being prong set allows for more light to bounce through the stone from all angles, bringing out more of the