1.54 Art Deco Marquise Diamond Engagement Ring in Platinum1. 54 Art Deco Marquise Diamond Engagement Ring in Platinum. The primary stone has a very faint, creamy yellow tone that adds a bit of elegant contrast to the colorless accent diamonds. Four . 10 carat accent marquise diamonds are angled at either side of the primary gemstone, creating an elegant junction from center stone to the platinum band. Two . 09 carat secondary accent diamonds rest on the shoulders of the band. This Art Deco ring is angular