What karat gold is 75% pure?

What karat gold is 75% pure? 18 karat gold is 75% pure by mass.

The karat system divides an alloy into 24 parts. In 18-karat gold, 18 of those 24 parts are gold, while the remaining six parts are other metals. The calculation is 18 ÷ 24 = 0.75, or 75%. The same purity is often marked “750,” meaning 750 parts gold per 1,000 parts of alloy.

The added metals are not merely fillers. Silver, copper, zinc, palladium, or other metals can make gold harder, change its color, and improve its suitability for jewelry. Pure or nominally 24-karat gold is relatively soft, so 18-karat alloys are widely used for rings, watches, and gemstone settings.

A common mix-up is confusing karat with carat. Karat measures gold purity; carat measures gemstone weight. Also, 18-karat gold is not 18% gold: the number refers to 18 parts out of 24. The neighboring standards are 14 karat, about 58.3% gold, and 22 karat, about 91.7% gold.