Three Stone Sapphire & Diamond Engagement Ring Art Deco PlatinumThree Stone Sapphire Diamond Engagement Ring Art Deco in Platinum. The center stone is a cornflower blue sapphire that weighs 1. 39 carats. The sapphire is flanked by two glittering old European cut diamonds that total 1. 01 in carat weight. The three main gemstones are all set with fishtail prongs that are bordered with milgrain engravings. There are also three baguette diamonds on each shoulder of the ring. A gorgeous example of sleek Art Deco