Pure gold is traditionally rated as how many karats?

Pure gold is traditionally rated as 24 karats.

The karat system measures gold purity in parts out of 24. Thus, 24-karat gold represents the full 24 parts of gold, while 18-karat gold contains 18 parts gold and 6 parts other metals, or 75% gold by mass.

In practice, “24 karat” does not always mean laboratory-perfect 100% purity. Commercial fine gold is commonly marked 999 or 999.9, meaning 99.9% or 99.99% gold. Absolute purity is difficult to achieve, so the karat designation is a conventional trade standard.

Lower-karat gold is often more practical for jewelry. Copper, silver, nickel, or palladium can be added to increase hardness, change color, or reduce cost. That is why 22-karat, 18-karat, and 14-karat jewelry may be more durable than very soft 24-karat gold. “Karat” for gold purity is also distinct from “carat,” the unit used for gemstone weight.