What Is a Troy Ounce and Where Did It Originate?

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What Is a Troy Ounce and Where Did It Originate?, photo courtesy of Metals.com

For collectors and investors of precious metals, the term that typically used to measure gold, silver, and other bullion is the troy ounce. While a troy ounce is the standard unit of measurement for precious metals, it is actually different than a standard ounce.

The difference can be dated back to the Middle Ages in the town of Troyes. In addition to being the production home to clothing manufacturer Lacoste, Troyes was once an important international trading center. Because of its role in international commerce, merchants would buy and sell goods from around the world, using a standardized weight system that would make it easier to facilitate trade. This standard weight would also be adopted by King Henry II of England soon after and used as the official standard of measure for gold and silver in Britain as well as in the U.S.

Today, when buying and selling gold and silver bullion worldwide, the troy ounce is used as the standard unit of measure. The spot price associated with gold and silver is designated as a troy ounce. The American Gold Eagle coin, as well as the Silver Canadian Maple Leaf coin, are minted in the standard troy ounce and both can be purchased from Metals.com. It is true that coins and other bullion are also minted in fractions of a troy ounce or in grams, but the spot price is set at a troy ounce and everything else is derived from that unit of measure.

When measuring other items, such as food, a designated ounce is different than a troy ounce. More specifically, a troy ounce is approximately 10 percent heavier than a standard or “avoirdupois” ounce. Reputable dealers, such as Metals.com, will sell precious metals bullion in weights consistent with the measurement of a troy ounce, whether it be a single ounce, 5 ounces or more. It’s also worth noting that a metal such as a copper coin is weighed at the standard ounce, not the troy ounce. Copper coins are also significantly less expensive than other “precious metals” such as gold and silver, and often available for about $1 per ounce.

When buying gold and silver bullion, it’s always good to remember that a troy ounce is not a standard ounce but rather a bit heavier.


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