Jump rings are particularly useful when joining jewelry like bracelets or necklaces with each other because they can be easily removed without damaging the bond between the pieces. Metal jump rings will be sold in sizes ranging from 4mm up to 2mm. This is due to how thick the metals are, which can range from 20 gauge (the thinnest) for platinum and 18k gold all the way up to 16 gauge (most common for sterling silver). Typically, jump rings are made from metal, but they can also be made out of a variety of different materials such as plastics, resins, and even paper. The widest selection is available in metals like silver, brass, copper and steel.