Karat and Carat

If you are currently in the market to purchase a diamond, or have been in the past, you may be familiar with the "4 Cs" most experts say are key when it comes to selecting a stone. The 4 Cs include: cut, carat, color and clarity.

What you may not know is the difference in the words "carat" and "karat." While the two sound the same and are similar in spelling, their meanings are not the same.

How Do You Know Which Word Is Correct?

The origin of both words dates back quite some time and is very interesting. Have you ever heard the term "carob," which refers to a common substitute for chocolate? Well, carob trees have reportedly grown in the Mediterranean region since ancient times and, surprisingly, carat and karat can both be traced back to the word carob.

The trees produce small, edible seed pods, which contain carob beans. Because carob beans are remarkably consistent from bean to bean, in terms of their size, they are also typically all extremely similar in terms of weight – regardless of when or where they have been harvested. Their unique weight characteristic led ancient people to adopt the carob beans as a reliable unit of weight.

According to some historians, Greeks were the first documented users of carob beans for weight. By 1500, Latin alchemists, continued using carob beans as a basic unit of weight, measured things by the "carratus." Carat and karat are the modern derivatives of carratus. Although they have a common origin and are pronounced the same, carat and karat now have different meanings when buying fine jewelry.

A carat is a unit of weight in a gemstone. Carat is abbreviated as c. or ct., while karat is k. or kt. How much does a carat weigh? Prior to 1913, a carat in the United States weighed 205.3 milligrams. In 1913 the United States accepted 200 milligrams as the international standard weight of a carat in jewelry. (European countries and Japan had accepted this standard earlier). For those of us who still think in pounds and ounces, it takes about 142 carats to make an ounce. The important thing to remember when buying fine jewelry is that a carat is a unit of weight, not a unit of size. One carat of a dense (heavy) stone will be smaller than one carat of a lighter stone. For example, a one-carat sapphire will be smaller than a one-carat diamond, because sapphires are heavier than diamonds.

A karat refers to the quantity of pure gold contained in a particular piece of fine jewelry. The measurement uses a base of 24 units. Pure gold is twenty-four twenty-fourths (24/24ths) gold, and is called 24-karat gold. As gold is a soft metal, other metals are often added to make it harder. Gold with other metals added to it is referred to as a gold alloy. The most common metals used in gold alloys are silver, copper, nickel, and zinc. Gold that is 14-karat gold is fourteen twenty-fourths (14/24ths) gold and ten twenty-fourths (10/24ths) other metals. The most common gold alloys are 14-karat gold and 18-karat gold. Other alloys, such as 16-karat gold, are sometimes available. When buying fine jewelry made of gold, or other objects made from gold, remember that the higher the number of karats, the higher the proportion of gold. Only 24-karat gold is 100% gold.