Bullion specifications become much easier to read once three ideas are separated: total weight, the unit used and the proportion of precious metal.
The troy ounce
Precious metals are commonly measured in troy ounces. One troy ounce is approximately 31.1035 grams. It is heavier than the everyday avoirdupois ounce used for many groceries and household goods.
What fineness means
Fineness expresses purity in parts per thousand. A piece marked .999 fine is represented as 99.9% of that metal. Fineness does not describe the total size of the piece.
Fine-metal content
To estimate fine-metal content, multiply total weight by the fineness proportion. A ten-gram item at .999 fineness contains approximately 9.99 grams of the stated metal, subject to production tolerances.
Read the whole specification
Check the stated metal, weight, unit and fineness together. Clear listings reduce confusion and make meaningful comparisons possible.