18 inch 1.3mm rhodium-plated sterling silver Water Wave chain.

Rhodium plated silver is sterling silver coated in rhodium to make it whiter and brighter. Silver is a softer metal, so rhodium protects it from scratches or wear. Solid silver is too soft to be fashioned into jewelry, so it contains 92.5% silver and 7.5% of other metals like copper, nickel, or a combination of the two. The traces of copper and nickel in sterling silver cause tarnishing. Adding rhodium plating prevents this from happening.