Tis forTarnish

Something made from metal is tarnished if it has a layer of a dull, colored substance on it instead of being bright, shiny and reflective. Tarnish is a different color on different kinds of metal. silver tarnish is black and copper tarnish is green. Some metals do not tarnish, instead they rust, which can eat away all of the metal over time instead of just leaving a thin coating on the surface.