Diamond Engagement Ring 18kt Yellow Gold & Platinum. A solitaire style diamond ring in 18kt yellow gold. This ring is set with one round brilliant cut diamond (0.47ct) in a six-prong platinum setting. The ring was cast, assembled and handset with a bright polished finish.The size 7 1/4 ring is hallmarked: 18K CCC and is in good condition (the prongs and shank are slightly bent). Included is an insurance appraisal of $2685.00.