A grain is a unit of weight that is commonly used in the measurement of precious metals like gold and silver. One grain is equal to 0.06479891 grams, or 0.002285714 ounces. This means that there are 15.43235835 grains in a gram, and 437.5 grains in an ounce.

Troy weight is a system of measurement that is used specifically for weighing precious metals. In the troy system, one pound is equal to 12 ounces, and one ounce is equal to 20 pennyweights. This means that one troy pound is equal to 240 pennyweights, or 5,760 grains.

The troy system originated in the city of Troyes in France, and was used by goldsmiths and jewelers to weigh gold, silver, and other precious metals. It was also used by medieval merchants to weigh spices and other goods.

Today, the troy system is still used in the measurement of precious metals, and is often used in the pricing of gold and silver. For example, the price of gold is commonly quoted in dollars per troy ounce.

In addition to its use in the measurement of precious metals, the troy system is also used in the measurement of gunpowder, as well as in the casting of bullets and other ammunition. It is also used in the measurement of medical prescriptions, where a grain is used as a unit of measurement for the active ingredients in certain medications.

Overall, the troy system is an important part of the measurement and trade of precious metals, and continues to be used by jewelers, goldsmiths, and other professionals who work with these materials. Be sure to read Gold and Gems Units of Weight for more information.