Vintage Petri Jewelers Emerald Cut Aquamarine Diamond Ring. This cocktail ring features a fabulous 7 carat emerald cut aquamarine and is accented by six (6) round diamonds totaling .24 carats. Finished in platinum, the aquamarine is prong set and the accent diamonds are bead set in a tight cluster on either side. The very open gallery provides an adequate amount of light into the center stone, allowing its natural blue to sparkle in any light condition.