Jewelry: Troy Ounce

Troy weight is a system of units of mass customarily used for precious metals and gemstones Troy Ounce: Troy ounce of a fineness of 999.9 parts per 1,000 parts, equal to 31.1034 grams. History Troy weight originates from what was called the troy system of mass. Dating back to before the time of William the Conqueror, the name comes from the city of Troyes in France, an important trading city in the Middle Ages. Units Troy ounce A troy ounce, the only currently used unit of the system, is 480 grains, somewhat heavier than an avoirdupois ounce (437.5 grains). A grain is exactly 64.798 91 mg, hence one troy ounce is exactly 31.103 476 8 g, about 10 per cent more than the avoirdupois ounce, which is exactly 28.349 523 125 g. The troy ounce is the only ounce used in the pricing of precious metals, such as gold, platinum, and silver, and this is the only remaining use of the troy ounce. In troy weight, there are 12 ounces in a pound, rather than 16 in the more-common avoirdupois system. Troy pound A troy pound is 5760 grains (about 373.24 g), while an avoirdupois pound is 7000 grains (about 453.59 g). 1 troy ounce = 31.1034768 grams Conversions Unit Grains Grams Pound (12 ounces) 5760 373.241 72 Ounce (20 pennyweights) 480 31.103 477 Pennyweight 24 1.555 173 8 Grain 1 0.064 798 91

Also see Gold History Jewelry History Gems Index

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia Troy Ounce.

History of Jewelry: Troy Ounce