Karats of gold are a measure of the purity of gold, frequently used to classify jewelry. Often the word karat is abbreviated with a “K” following a number, such as 24K, 18K, and 14K.
Here are the most common karats of gold and their purity.
24K Gold – This is gold that is 99.9 percent or greater in gold purity, essentially pure gold. Pure gold is bright yellow. Pure gold is sometimes molded into the shape of bars or coins for investment purposes. Pure gold is ordinarily not made into jewelry because it is a relatively soft and malleable metal.
22K Gold – This is gold that is 22 out of 24 parts pure, or 91.67 percent pure gold. The rest of the item may be composed of silver, zinc, copper, nickel, or another metal. This level of purity is used in jewelry and for making coins. Other metals are alloyed with gold to increase its hardness or durability.
18K Gold – This is gold that is 18 out of 24 parts pure, or 75 percent pure gold. This is a common standard for making jewelry in Europe. This is a relatively high level of purity for jewelry, alloyed with other metals to make the jewelry durable.
14K Gold – This is gold that is 14 out of 24 parts pure, or 58.3 percent pure gold. This is a common standard for jewelry made in the United States and many countries. Because gold is a relatively expensive metal, this level of purity is more affordable for the common person. As this gold is alloyed with a relatively large percentage of another metal or other metals, it is generally quite durable.
10K Gold – This is gold that is 10 out of 24 parts pure, or 41.7 percent pure gold. This is a common standard for jewelry. This is relatively diluted gold that becomes increasingly popular as the price of gold moves higher. In the United States, this is the lowest level of purity acceptable for being deemed gold.
Besides adding durability, gold may be alloyed with particular metals to alter its color. Copper is known to make gold appear more pink, and silver and platinum can give gold a white appearance.