Sterling Silver with 1.8ctw Blue Topaz & Lab Created Moissanite Halo Cluster Adjustable Engagement Anniversary Promise Birthstone Ring. Celebrate your romance with this sterling silver adjustable ring, perfect for an anniversary, engagement, anniversary, or birthday (December birthstone) with a round brilliant cut blue topaz. Glittering round brilliant cut lab created moissanites frame this center stone in a tulip halo cluster and have VVS1 clarity and D color. An adjustable shank allows this pretty ring to accommodate your finger size.