Why are Troy Ounces Important?
If you buy a one ounce gold coin and place it on a standard grocery store scale, you would find that it's approximately 10% heavier than an ounce of beef. The two measures are not the same. Many people don't realize this, which is why they often fall victim to sellers who try to boost the value of their products by simply listing them in ounces. For example, a seller could claim that a precious metal weighs 100 ounces; however, you would be losing around 10% of its value because it actually only weighs 90 troy ounces.
It may seem like an unnecessarily complicated system, but here are good reasons that precious metals have their own unit of measure. The troy was retained as the standard unit of measurement over the avoirdupois ounce to ensure purity standards and other common measures remained consistent over time.
Troy Ounces vs. Avoirdupois Ounces
How is an ounce of gold different from an ounce of sugar? While the gold is measured by troy ounces, goods such as sugar or other items are measured using avoirdupois ounces. The name might sound completely strange to you, but the avoirdupois is the unit of measure that we use to weigh almost everything else other than precious metals. The scales at the grocery store and the scales in your bathroom weigh things in avoirdupois ounces. Because the avoirdupois ounce is so common, we simply refer to it as "ounces".
Obviously, then , a troy ounce is a bit heavier than a regular ounce. One regular ounce is 28.35 grams, while a troy ounce is 31.1035 grams. The weights are close, but the difference becomes very noticeable when you're trading in larger quantities of precious metals.
Here is where it can become confusing. The troy system was indirectly derived from the Roman monetary system using 12 troy ounces to make up one troy pound. This makes a troy pound lighter than a regular pound, even though troy ounces are heavier. This is only possible because fewer troy ounces are needed to make a pound - 12 as opposed to 16 ounces for a regular pound.
Even though the system can seem confusing at first if you aren't very familiar with it, it does get easier. If you ever come across an item that is being weighed in avoirdupois ounces, you can easily convert it to troy ounces. Simply multiply the given amount by .91 to find the equivalent weight in troy ounces. You may also want to take note that copper, being a base metal, is weighed using the avoirdupois ounce. If you are going to be buying copper bullion, be sure to keep this in mind.
As you can see, it's important that any buyer of precious metals has a thorough understanding of the troy ounce if he or she wants to safely and smartly navigate the precious metal market.
To learn more, contact your Professional Jeweller.