📖How to Read the Gold Price: Troy Ounces, Grams and Fineness

Published 2026-09-25 · 5 min read · Gold

The international quote is dollars per troy ounce, but jewellers sell by the gram. How the two relate, and how to value 18-carat gold.

A troy ounce is not a kitchen ounce

Precious metals are weighed in troy ounces: one troy ounce is about 31.1035 grams. The everyday avoirdupois ounce is about 28.35 grams — roughly 10% lighter. If you convert "one ounce of gold" using 28.35, you will understate the value by about a tenth. To turn a gram price into a troy ounce price, multiply by 31.1035; to go the other way, divide by 31.1035.

Why the quote is in dollars

XAU/USD means "how many US dollars one troy ounce of gold is worth", and it is formed by continuous dealing across London, New York, Zurich and other centres. Because the quote is in dollars, gold tends to move inversely to the dollar: a weaker dollar usually means it takes more dollars to buy the same ounce. This is why gold is often read as a mirror image of the currency.

Fineness: 24 carat is pure

The spot quote refers to pure gold of 99.9% or better — 24 carat. Jewellery is usually alloyed, because pure gold is too soft for settings and everyday wear. 18 carat is 75% gold, 14 carat about 58.5%. To estimate the metal value of an item, multiply weight by fineness and then by the current price. Ten grams of 18 carat contains 7.5 grams of gold; multiply that by today's gram price and you have its metal value.

Why the shop price is higher

Retail Jewellers add making charges, design costs, brand premium, tax and margin on top of the metal price — commonly 10% to 30% or more above the international quote. Buy-back prices sit below it, because the dealer absorbs assay, refining and financing costs. A two-way spread, buying above and selling below the benchmark, is normal market behaviour rather than a sign of bad faith.

How our gram figure is derived

The yuan-per-gram figure on this site comes from the dollar ounce quote in two steps: convert to yuan at the day's reference rate, then divide by 31.1035. It is a theoretical metal value with no making charge or premium included. It is well suited to comparing levels and judging where gold broadly stands, but it is not the same as a counter price in a shop.

What moves gold

Real interest rates — nominal rates minus inflation expectations — are the core driver: when real rates fall, the opportunity cost of holding a non-yielding asset like gold falls and the price tends to rise. Central bank buying, safe-haven demand during geopolitical uncertainty, the strength of the dollar and physical consumption, particularly in Asia, all matter too. Note that free data feeds are typically updated once a day, so sharp intraday moves will not appear immediately.

← Back to articles