* What it is: A troy ounce is equal to 31.1034768 grams (or 480 grains).
* Difference from an avoirdupois ounce: It's important to distinguish a troy ounce from the more common avoirdupois ounce used for everyday items. An avoirdupois ounce is lighter, weighing 28.3495 grams.
* Historical origins: The troy ounce originated from the medieval city of Troyes in France, where it was used as a standard unit for measuring precious metals.
* Why it's used: The troy ounce has been adopted internationally as the standard unit for measuring precious metals due to its historical significance and its ability to provide a consistent and accurate measure for trading and valuing these metals.
In summary, a troy ounce is a unit of weight specifically for precious metals, distinct from the avoirdupois ounce used for everyday items.