Troy weight

Troy weight is a system of units of mass that originated in the Kingdom of England in the 15th century.^[1] By far the most common troy unit is the troy ounce (oz t), the standard mass unit for precious metals in industry and in trade; it equals 31.1034768 grams. Other troy weight units are the grain, the pennyweight (24 grains), the troy ounce (20 pennyweights), and the troy pound (12 troy ounces). The troy grain is equal to the grain unit of the avoirdupois and apothecaries' systems, but the troy ounce is heavier than the avoirdupois ounce, and the troy pound is lighter than the avoirdupois pound.