Gold-plated jewellery is made up of a brass base and an alloy of copper and zinc, making it non-allergenic, solid and malleable.

This alloy is then electroplated with 3 microns of 18-carat gold. A micron is the thickness of gold that covers the jewel. In France, a minimum of 3 microns of gold is required for a piece of jewellery to be described as "gold-plated".

18-carat gold means that 100g of alloy contains 75g of "pure gold", i.e. 75.01%.