Every single coin that is produced no matter which denomination it is is guaranteed to be made from pure gold and must by law come from sources within the USA. But as well as containing the gold the coins will also have an alloy of silver and copper which makes them more resistant to wear. At all times the double eagle gold coin that are produced are not only backed by the United States Mint in relation to how much they weigh and what they contain, but original ones will need to have been authorized for production by Congress.