troy ounce
A troy ounce is the standard precious-metals weight unit, equal to about 31.1035 grams.
Why it matters
Gold and silver spot prices are commonly quoted per troy ounce, so UK buyers often need to convert product weights in grams into troy ounces before estimating metal value. Fine-metal content also depends on purity, so gross weight alone is not enough.
What to check
A troy ounce is heavier than a standard avoirdupois ounce of about 28.35 grams. Do not mix ounce systems, and check whether a product quote uses gross weight or fine-metal weight.