A gold coin is a coin that is made mostly or entirely of gold.
Traditionally, gold coins have been circulation coins, including coin-like bracteates and dinars. Since recent decades, however, gold coins are mainly produced as bullion coins to investors and as commemorative coins to collectors. While also modern gold coins are legal tender, they are not observed in everyday financial transactions, as the metal value normally exceeds the nominal value. For example, the American Gold Eagle, given a denomination of 50 USD, has a metal value of more than 1,000 USD.
The gold reserves of central banks are dominated by gold bars, but gold coins may occasionally contribute.
Gold has been used as money for many reasons. It is fungible, with a low spread between the prices to buy and sell. Gold is also easily transportable, as it has a high value to weight ratio, compared to other commodities, such as silver. Gold can be re-coined, divided into smaller units, or re-melted into larger units such as gold bars, without destroying its metal value. The density of gold is higher than most other metals, making it difficult to pass counterfeits. Additionally, gold is extremely unreactive, hence it does not tarnish or corrode over time.