The most important non-stock exchange market place for gold and silver is in London. At the London Bullion Market the global market price for gold has been determined since 1919. The London Bullion Market is a whole sale over-the-counter market. The minimum quantities traded amount in general to 1.000 ounces of gold and 50.000 ounces of silver. The mass system typically used for trading precious metals is the Troy ounce (oz). One oz of gold is equal to 31.1 grams. There are 32.15 Toy oz in 1 kilogram.