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What is a Troy Ounce?

At the KJC showroom we sometimes have clients come in assuming that an ounce of a precious metal is 28 grams, which of course is the standard metric weight (also known as the avoirdupois ounce). Within the bullion industry, in the West at least, we use a system known as the troy system in which 1 t/oz of precious metal is 31.103 grams. For instance, in a pure gold coin like the world-renowned Australian Kangaroo for instance, this coin is a pure gold coin, 24 karat or 99.99% pure gold. It will have a weight of 31.103 grams, making it a 1 t/oz pure gold coin. Whereas a coin like the U.S. mints gold eagle, can be a bit different. This coin also contains 1 t/oz of pure gold but does contain other metals to make the coin more durable, adding up to a total weight of 33.931 grams, which then in turn makes this coin 22 karat, or 91.67% pure gold within the coin. although it still contains 1 t/oz pure gold or 31.103 grams, there are other metals added the product so the overall purity of the coin does diminish, the South African Krugerrand is similar in this aspect. This can make things a bit confusing so I will explain the history behind the troy ounce and why we use it.

The English word Troy used as a term for weight was first recorded in 1390 by the Earl of Derby describing the weight of a platter while on a trip to France, and well, the name seems to have stuck. Whereas the troy ounce that we know today for its use in the bullion industry and coinage was officially adopted in 1527 by the British empire and was later standardised for much of Europe. Although the troy ounce has a long and illustrious history that stems from the Roman conquest of Europe… but I’ll go into that a bit later.

The troy ounce system has a few theories about how it came to be, in my opinion the most likely might originate from the town of Troyes in France – sound familiar? This town was a large trade hub in the Middle Ages, and merchants from all over the medieval world would travel here to trade their goods. There were many other measurements and systems that were used to value items during this time, and it was very confusing for various merchants especially when travelling internationally. The namesake of this town facilitated a need to standardise a system of weight to make the bartering system in place easier to work with. It was decided during the 13th century in England to standardize a weight system to help alleviate the stress and thus, the troy ounce was standardized.

In many ways the troy weight system, like many things we still use today, originated with the Roman Empire. It was their influence throughout Europe and much of the known world of that time that gave us the steppingstones to many of the systems in place today. The British and much of Europe had unofficially been using the old roman system for a millennia, as this was all they knew. The Romans would use bronze bars of varying weights as currency, one of these bars was called an “uncia” pronounced very similarly to an ounce in English today. This “ounce” bar was a 1/12th of a pound, 1 pound being the largest whole number in their measuring system, the rest of these weights were fractions of this larger whole. Very similar to how we use this system today. The most internationally recognized and most often traded gold bar has a weight of…..you guessed it, 1 troy ounce.

At KJC we have multiple different options for buying gold and silver whether it being the wonderful Australian Kangaroo series or Perth mint 1 oz minted and cast bars, we are widely known and respected for always having these extremely trade-able assets in stock.

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KJC Team

The Blog Team at KJC Coins Australia strives to bring you the latest happenings in the bullion market, new releases in numismatic and bullion products and in depth tips & tricks of the trade in a creative & easily digestible way. Keep up to date with us - we're only just getting started!
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