Measure of Purity
Karat is the measure of gold purity. Pure gold, or 24-karat gold, is soft and malleable so it’s mixed with other metals — copper, silver, palladium, or manganese — to make it strong enough to be worn. When another metal is added to 24-karat gold it changes the purity. An 18-karat gold piece, means it is 18 out of 24 parts gold and 6 parts alloy, 14-karat means 14 out of 24 parts are gold and 10 parts are alloy. The amount of gold versus alloy also changes the color.