This 13mm round, genuine, natural, Pinkish-Red Ruby Cabochon has been bezel set in sterling silver. The ring has a sterling silver backplate and a 3mm wide band. US Size 7. This is a perfect gift for someone born in July or for an anniversary gift for the 15th and 40th. According to the International Gem Society, a 13mm gemstone cabochon would be approximately 10.5 carats in weight.