Sterling Silver 3.5CT Round Lab-Created Moissanite Cluster Engagement Ring. Make the most of your special romantic moment by selecting this gorgeous, brightly polished sterling silver lab-grown moissanite engagement ring. A sparkling round brilliant cut lab-grown moissanite solitaire sits in a vintage 6-prong setting in the center. Smaller round brilliant cut lab-grown moissanite side stones trim the perimeter in a gorgeous flower cluster, all atop a comfortable flat-edged band.