Contrary to what most people think, Olympic gold medals are made mostly of silver not gold. They have not been made from solid gold since the 1912 Stockholm Olympics. The International Olympics Committee (IOC) has mandated that Olympic gold medals contain at least 0.21 oz (6 g) of gold, but they are usually silver with gold plating.
The actual composition of the medal varies from one Olympiad to the next. For example, the 2012 London Olympic gold medals contained 6% copper and 93% silver, with only 1.34% gold. Aside from the gold plating, a gold medal and a silver medal have virtually the same makeup; silver medals replace the gold with more copper. Exotic materials have been introduced into the medals in other Games, including jade for the 2008 Beijing Games.