.84 Mid-Century Diamond Engagement Ring in Platinum. 84 Mid Century Diamond Engagement Ring in Platinum. This Mid Century engagement ring features a . 84 carat genuine natural diamond in platinum. The enchanting primary diamond features elongated, boxy facets create a mosaic of light movement within the stone. Touches of fire flicker at the corners of the primary diamond creating a rainbow prism of colors. The gallery view of this ring is open work and perfectly polished. Set in four prongs and