SIZE: 30mm (35mm including ring) Sterling Silver is a white and highly reflective precious metal. Sterling is .925 percent pure, which sometimes will be indicated by a stamp on the metal. A lot of our silver is AT (anti-tarnish) protected. SIZE: 30mm (35mm including ring) Sterling Silver is a white and highly reflective precious metal. Sterling is .925 percent pure, which sometimes will be indicated by a stamp on the metal. A lot of our silver is AT (anti-tarnish) protected.