What is a Troy Ounce?

Collecting gold coins will eventually bring you to the point where you'll have to understand what the Troy Ounce is. The Troy Ounce is a measure of weight and part of the Troy weight system, which is named after the city of Troyes in France, and not after the city of Troy of the Trojan War in Greece.

The Troy Ounce is 31.1034768 gram, which is about 10% heavier than a usual or avoirdupois ounce, which is 28.349523125 gram. The Troy Ounce can be measured in grains and it's exactly 480 grains (comparing to 437.5 in a normal ounce).

The troy ounce is ultimately used for measuring mass of precious metals, black powder, and gemstones. The troy weight system was first used in British pre-decimal coinage in the 12th century, when the coin denominations showed literally its contents of gold or silver.

The weight of gold coins, especially modern bullion gold coins, is quite often aligned with troy ounce or its fractions or multiplies, so the usual weights of gold coins can be: 1 troy ounce, half ounce, quarter ounce, tenth ounce, and now they even do twentieth ounce, which is a tiny coin weighing only 1.5 gram.

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