every precious metal product consists to a certain extent of the precious metal itself and other substances. The usual purity for gold and silver today is 999/1000, although purity grades up to 999.99/1000 are technically possible and are used for individual special coins. However, such a high purity also requires technically far more complex processes. Even at 999/1000, a product is considered “pure,” since a tiny residue of foreign matter is always present. To achieve the specified fine weight, bars and coins are always slightly heavier than specified. In addition, there are also coins made of alloys, but in order to be considered bullion coins must have a minimum fineness of 900/1000.