What is a troy ounce?
What is a troy ounce?
A troy ounce indicates the actual precious metal weight, i.e., the weight of the fineness of a precious metal . The weight in troy ounces is calculated by multiplying the total weight of the alloy by its fineness, or by subtracting the base metal content of the alloy from the total weight.
A troy ounce is a troy ounce of pure gold – named after the important medieval trading city of Troyes in France.
The troy ounce as a unit of measurement
While the troy pound was abolished in Great Britain in 1878, the troy ounce was initially retained for weighing precious metals and gemstones . However, in 1963, the Weights and Measures Act restricted the use of the troy ounce to determining the fineness of precious metals.
In England and the USA, the price of gold, silver, or platinum bars is still quoted in US dollars per troy ounce. There are also significant quantities of precious metal coins circulating there that have their weight based on the troy ounce—there are coins of 1/10 troy ounce, ¼ troy ounce, ½ troy ounce, or one troy ounce.
Differences to other ounces
A troy ounce differs in weight from the standard avoirdupois ounce, which weighs 28.35g. The differences can be explained by the fact that the measurement system came into contact with and was influenced by other systems during its spread. Like the apothecary ounce, the troy ounce weighs exactly 31.1034768g.
