The ounce on your kitchen scale and the ounce in a gold quote are not the same unit. Here is the difference.
Every gold quote on every screen on earth is denominated in a unit most people have never weighed anything with. The troy ounce is a medieval survivor, and its story explains a surprising amount about how the metals world thinks.
The unit takes its name from Troyes, a market town in the Champagne region of France whose great medieval trade fairs set standards merchants across Europe could rely on. When you weigh silver by the troy ounce today, you are using a convention that predates Columbus, one that survived precisely because everyone who mattered agreed on it.
The troy system is built on the grain, historically tied to a grain of barley, at exactly 480 grains to the troy ounce. That works out to about 31.1035 grams, roughly ten percent heavier than the avoirdupois ounce of 28.35 grams on your kitchen scale. Twelve troy ounces make a troy pound, which is why old texts speak of pounds of silver that weigh less than you would guess.
When global bullion trade standardized in London, the troy system was already the shared language of mints, refiners, and assayers, and switching units in a market built on precision would have invited a century of costly confusion. So it stayed. Every LBMA benchmark, every futures contract, every mint specification, and every coin listing you will ever read speaks troy.
Coin specifications are where the unit gets personal. A Morgan or Peace dollar contains .77344 troy ounces of pure silver. A pre-1933 double eagle carries .9675 troy ounces of gold. A modern American Silver Eagle holds exactly one. Knowing these numbers lets you translate any quote on our live markets page into the metal value of the coin in your hand, which is the foundation under every melt-versus-numismatic conversation.
When a listing says "1 oz .999 fine," both halves matter: one troy ounce of weight, 99.9 percent purity, so the pure metal content is the product of the two. That simple multiplication, weight times fineness, is the whole arithmetic of bullion, and the troy ounce is the unit that makes it universal.