Troy weight
Troy weight is a system of mass units traditionally used for precious metals and gemstones. Its pound contains 12 ounces, each of 480 grains.
Grain (unit): A unit of mass equal to 1/480 of a troy ounce or 1/7000 of an avoirdupois pound. The grain is the common base unit that fixes the size of every troy unit.
Gold bullion: Gold held in bulk form, typically as bars or coins valued chiefly for its metal content. Bullion markets commonly state gold mass in troy ounces.
Troyes: A city in northeastern France that hosted major medieval trade fairs. The name “troy” is traditionally associated with this city’s fairs, though the origin is uncertain.
Apothecaries' system: A historical system of weights used in pharmacy, with units including the grain, scruple, and dram. It shares the troy ounce’s 480-grain basis but divides and names units differently.
Troy ounce: A mass unit equal to 480 grains, or about 31.1035 grams. This is the system’s defining everyday unit for weighing precious metals.
Silver bullion: Silver held in bulk form, typically as bars or coins valued chiefly for its metal content. Silver bullion is commonly weighed and priced using troy ounces.
Champagne fairs: A cycle of major medieval trade fairs held in the County of Champagne. Their international commerce helped spread standardized weighing practices across Europe.
Avoirdupois ounce: A mass unit equal to 1/16 of an avoirdupois pound, or about 28.35 grams. Comparing it with the troy ounce exposes the danger of treating ounces as interchangeable.
Troy pound: A mass unit equal to 12 troy ounces, or 5760 grains. Its twelve-ounce structure distinguishes the troy pound from the more familiar sixteen-ounce pound.
Precious metal: A scarce, valuable metal such as gold, silver, or platinum, prized for its economic and material properties. Troy weight’s enduring commercial role centers on measuring precious metals.