.55 Old Mine Diamond Sapphire Engagement Ring in Platinum. This future classic engagement ring features a .55 carat old mine cushion cut diamond and a halo of blue sapphires in platinum. The glittering center diamond reflects a classic white hue. The accent sapphires elegantly halo the center stone. Additional accent diamonds decorate the slender shoulders. Finished in polished platinum. Dainty with an expert design. This breathtaking engagement ring is complete with delicate milgrain detailing around the stones.