Troy ounce
A troy ounce is the standard unit of weight for precious metals, equal to 31.1034768 grams. It is about 10% heavier than the ordinary avoirdupois ounce (28.35 g) used in everyday commerce. All spot prices, bar weights, and coin denominations in bullion are denominated in troy ounces.
The troy ounce traces back to medieval European weight systems used in the city of Troyes, France. While most countries adopted the metric system, the troy ounce persists as the global standard for precious metals because it is built into centuries of contracts, exchange specifications, and refining standards.
A 1 oz Gold Maple Leaf contains exactly one troy ounce (31.1 g) of pure gold. A 1 kg gold bar is 32.151 troy ounces. A common mistake is to confuse troy ounces with the regular ounce — silver shoppers sometimes order assuming the lighter unit.
Related terms
The spot price is the live wholesale market price for one troy ounce of pure gold (or silver) delivered immediately. It is set continuously by the LBMA, COMEX, and other major markets. Retail bullion always trades above spot, with the markup called the premium.
Fineness is the purity of a precious metal item, expressed as parts per thousand. A 1 oz Gold Maple Leaf at .9999 fineness is 99.99% pure gold. Investment-grade gold for VAT exemption in the EU must be ≥99.5% fine (995/1000). Common levels: .999, .9999, .99999.
LBMA Good Delivery is the international quality standard maintained by the London Bullion Market Association. A refiner on the LBMA Good Delivery List has proven its bars meet strict purity (≥99.5% gold, ≥99.9% silver), weight, dimensions, and assay accuracy — making the bars universally accepted by major dealers.