Gold plating is a process where a thin layer of gold is bonded onto a base metal. Plating is quite common in the jewelry world, with gold and rhodium being two popular types. This process was invented by an Italian chemist, Luigi Brugnatelli in 1805, the first person to plate a thin coat of gold onto silver.
Gold plating is commonly used for costume jewelry or to mimic more expensive pieces. It is almost impossible to tell apart expensive pieces of gold jewelry from inexpensive gold plated imitations. Gold plating of silver is used in the manufacture of jewelry. The thickness of gold plating on jewellery is noted in microns (or micrometers). The microns of thickness determines how long the gold plating lasts with usage. The jewellery industry denotes different qualities of gold plating in the following terminology Gold flashed / Gold washed - gold layer thickness less than 0.5 micron Gold plated - gold layer thickness greater than or equal to 0.5 micron Heavy gold plated / Vermeil - gold layer thickness greater than or equal to 2.5 micron Gold plated silver jewellery can still tarnish as the silver atoms diffuse into the gold layer, causing slow gradual fading of its color and eventually causing tarnishing of the surface. This process may take months and even years, depending on the thickness of the gold layer. A barrier metal layer is used to counter this effect - these can be nickel or rhodium. Copper, which also migrates into gold, does so more slowly than silver. The copper is usually further plated with nickel. A gold-plated silver article is usually a silver substrate with layers of copper, nickel, and gold deposited on top of it.