This round square stack has three rings: 1 thick silver (5mm), 1 very thick (3mm) oxidized, and 1 thin gold band. This ring is available in sizes 5.0 – 11.5, including all half sizes. Special note: because of the wideness of the stack rings, it is recommended to buy a stack that is 1/2 size larger than your normal ring size. Materials: sterling silver (.925), oxidized sterling, and 14k gold-fill (14k gold over a brass core/no nickel). The black (oxidized) components of our jewelry will wear over time and eventually achieve a beautiful antique-like finish. All materials are hypoallergenic. This ring is handmade in our California and New York production studios.