A bullion coin is a coin struck from precious metal and kept as a store of value or an investment, rather than used in day-to-day commerce. Investment coins are generally coins that have been minted after 1800, have a purity of not less than 900 thousandths and are or have been a legal tender in their country of origin. Bullion coins are usually available in gold and silver, with the exception of the Krugerrand and the Swiss Vreneli which are only available in gold. The American Eagle series is available in gold, silver and platinum, and the Canadian Maple Leaf series is available in gold, silver, platinum and also palladium.
Bullion coins are also typically available in various weights. These are usually multiples or fractions of 1 troy ounce, but some bullion coins are produced in very limited quantities in kilograms and even heavier.
Bullion coins sell for a premium over the market price of the metal on the commodities exchanges. This is due to their comparative small size and the costs associated with manufacture, storage and distribution. The margin that is paid varies depending on what type of coin it is, the weight of the coin, and the precious metal. The premium also is affected by prevailing demand.
The ISO currency code of gold bullion is XAU. ISO 4217 includes codes not only for currencies, but also for precious metals (gold, silver, palladium and platinum; by definition expressed per one troy ounce, as compared to "1 USD") and certain other entities used in international finance, e.g. special drawing rights.