Below is a list of Rhodium Plating manufacturers from Downers Grove, Illinois. Rhodium plating refers to the process of depositing a thin layer of the chemical element rhodium (Rh) onto a conductive metal surface. As a chemical element, rhodium is a particularly rare substance, and features a silver-white color. A very hard and chemically inert element, rhodium is a transition metal and is categorized as being part of the platinum group metals (PGMs), meaning that rhodium has the shared characteristics of excellent catalytic properties and wear-resistance.