Vintage Deco Cushion Sapphire Engagement Ring Platinum.  This Art Deco engagement ring features a 1.38 carat cushion cut sapphire with .18 carats of round accent diamonds and is set in platinum. The sapphire has a deep blue color and the bright accent stones bring sparkle and contrast. There is fine milgrain detail on the basket and delicate engraving at the bottom of the shoulders.