Troy ounce is a traditional unit of gold weight. Troy weight is a system of units of mass that originated in 15th-century England, and is primarily used ounces in french press the precious metals industry.
Troy weight probably takes its name from the French market town of Troyes where English merchants traded at least as early as the early 9th century. Many aspects of the troy weight system were indirectly derived from the Roman monetary system. The Romans used bronze bars of varying weights as currency. United States coinage by Act of Congress on May 19, 1828. The troy ounce and grain were also part of the apothecaries’ system.
The only troy weight in widespread use today is the British Imperial troy ounce and its American counterpart. Both are currently based on a grain of 0. The origin of the troy weight system is unknown. Although the name probably comes from the Champagne fairs at Troyes, in northeastern France, the units themselves may be of more northern origin. Then troy weight is a style of weighing, like auncel or bismar weights, or other kindred methods. The troy weight then refers to weighing of small precious or potent goods, such as bullion and medicines. Troy, merchant, avoirdupois and London pounds.
A troy ounce weighs 480 grains. That agreement does not define any troy weights. An avoirdupois pound is approximately 21. One pennyweight weighs 24 grains and 20 pennyweights make one troy ounce.
The d in dwt stands for denarius, the ancient Roman coin that equates loosely to a penny. There is no specific ‘troy grain’. Mint masses, also known as moneyers’ masses were legalized by Act of Parliament dated 17 July 1649 entitled An Act touching the monies and coins of England. A grain is 20 mites, a mite is 24 droits, a droit is 20 perits, a perit is 24 blanks.