Diamond & Sapphire Halo Engagement Ring PlatinumDiamond Sapphire Halo Engagement Ring Platinum. This fabulous modern engagement ring features a . 74 carat round brilliant cut diamond with a . 36 carat sapphire halo and set in platinum. The enchanting sapphire halo features calibre cuts that perfectly contour to the shape of the milgrained channel holding the bead set diamond. The sapphire halo is interrupted by a slight box holding one small accent diamond which continues down to the simple