2.85 Carat Cushion Sapphire Engagement Ring in Platinum2. 85 Carat Cushion Sapphire Engagement Ring in Platinum. This dazzling modern engagement ring features a 2. 85 carat cushion cut sapphire with trapezoid shaped diamond accents weighing . 80 carats and is set in platinum. The stunning sapphire has a dark cobalt color which stands out even more due contrast with the bright high polish of the double prongs. The lines of the trapezoid diamonds run perfectly into the edges of the cushion cut sapphire and