A unit of measure for weight that dates back to the Middle Ages. Originally used in Troyes, France, the troy ounce was used when dealing with precious metals. One troy ounce is equal to 31.1034768 grams.

|||The troy ounce is the only measure of the troy weighting system that is still used in modern times. It is used in the pricing of metals such as gold, platinum and silver. When the price of gold is said to be US$653/ounce, the ounce being referred to is a troy ounce, not a standard ounce. There are 14.58 troy ounces in one pound.