Two of the most common types of gold are 14K and 24K. The "K" refers to karats. This is a measure of how much pure gold is contained in the alloy compared to other metals that are combined with it.
All gold is an alloy, since it is impossible to remove all the impurities. However, 24K gold is considered "pure gold," even though it is 99.9 percent pure. Fourteen-karat gold is 58.3 percent gold. Gold is usually mixed with silver or copper.
Since 24K contains more gold, it has more gold color and luster than 14K gold. Twenty-four karat gold is a deeper yellow color when compared to 14K gold.
Fourteen-karat gold is hard to the touch, as are most other metals. Twenty-four karat gold is soft and is easily bent and dented with bare hands.
Fourteen-karat gold is commonly used in jewelry and other fine luxury items. Twenty-four karat gold is almost exclusively used for gold bullion.
Twenty-four karat gold sells at a very high premium compared to 14K gold. Nearly twice as much gold is contained in 24K gold, and it costs more to purify.