Use care when buffing Gold Filled, to avoid removing the gold layer. The surface layer of karat gold is usually 10kt, 12kt or 14kt. Nickel Silver contains no sterling silver, although it is silver in color. Oxygen , Nitrogen, Hydrogen, Iron, Copper and Niobium are elements. Elements are the basic building blocks of chemistry.
Metal alloys are mixtures of various elements.
Brass is an alloy of Copper, Zinc and other metals. Sterling silver is an alloy of Silver and Copper. One of the more common metal allergies that your customers may have, is an allergy to nickel. People with slight nickel allergies can usually wear Surgical Stainless Steel for a few hours, or possibly all day. But some people are so sensitive that they can not even wear watches, or have the buttons on their Levis touch their skin.