Plate, Plating. A very thin layer of metal deposited on a base metal by the process of electroplating. Metals of an inexpensive alloy or composition are plated with a more expensive metal; for example zinc is plated with copper; brass, bronze, copper, nickel-silver, white metal is plated with silver; and any of these are plated with gold. Thus the plated object – manufactured at low cost – can be given the finish, color and texture of the more expensive metal.

The thickness of the plating, achieved by a longer time in the plating tanks, is very important, particularly if the item is to be used or worn. A bright plating can be added to increase the reflectiveness, hardness and wearing qualities of the piece; this is done by introducing a small amount of a second metal (as a separate anode added to the tank or a separate tank) enhances the metal, as silver is enhanced with rhodium for example. (See bright plating, electroplating.)

Identifying the base metal after it has been plated is not easy. Test cuts are made to detect the color of the base metal – that may be the same or slightly different (as copper will appear pink; see bleeding).

The word "plate" is also used in additional ways in the numismatic and medallic field: (1) the one side of a box medal; (2) the planchet for side-by-side dies at the Paris Mint for striking their Restrike Series; (3) large plates (like dinner plates that have been embellished with medallic items), and (4) a plate coin or medal is one that is pictured in a catalog or book.