To make gold plated jewelry numerous plates of metal are 'laminated' mechanically by soldering, brazing, or welding. The gold used in plated gold jewelry is 10 karats or greater in fineness. Gold filled or rolled gold jewelry is not as durable as solid gold fine jewelry. The layer of gold on gold plated jewelry is extremely thin. Differing thicknesses of gold can be applied to the base metal to increase the durability of gold plated jewelry. Gold plated jewelry generally has a thinner gold covering than gold filled jewelry.
How to tell how much gold is in gold plated jewelry.
Markings have been added to newer gold jewelry to enable buyers to know how much gold they are buying and what karatage the gold plating is. A marking that says 1/20 12K G.F. means that the gold filled jewelry is at least 1/20th of 12 karat gold by weight.
Why does gold plated jewelry lose its gold colour?
Gold plated jewelry has a tendency to lose its gold colour. With a normal plating thickness this can be in as little time as a year. Why is this? Usually, gold plating is added over silver. Silver and gold can be reactive together and so the gold is gradually diffused into the silver and the silver comes to the surface and is diffused into the gold. It is not that the gold is wearing off, rather silver is coming to the surface and the gold is receding into the silver, making the gold plated jewelry lose its gold colouring. Tarnishing can also occur to the gold plated jewelry when silver has reached the surface.
The solution to this problem is to put a copper over the silver and then the gold over the copper. Copper is still reactive to gold but not as much as silver. The jewelry piece will still lose its gold colouring but not as quickly as with just silver.
For gold plated jewelry that does not lose its gold colouring, nickel is added as a barrier between the gold and silver or copper. Nickel does not migrate through gold and so a long lasting gold plated jewelry piece is able to be created. However, some people can have a reaction to nickel so it is best to keep this in mind if purchasing this type of gold plated jewelry.
Gold plated jewelry is not an investment in gold jewelry. It is used almost exclusively in costume or party jewelry.