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What is the Difference Between Carat and Karat?

What is the difference between Carat and Karat? Even though they are pronounced the same way, Carat and Karat are different units of measurement. Carat with a "C" is the measurement used when referring to a diamond or gemstone. And Karat with a "K" measures the purity or fineness of a metal, such as gold.


Many believe that Carat refers to the size of a diamond or gemstone. However, Carat refers to the weight. There are 100 points in a Carat and 50 points is half of a Carat. It is similar to pennies in a dollar. Carat is abbreviated as Ct. or Ctw. Ctw stands for Carat total weight which is the total weight of all of the diamonds or gems in a ring or piece of jewelry. Jewelers will use weighing scales, like the ones shown below, to determine the weight.

Diamond scales to show carat weight

The term Carat was derived from the carob tree. Before scales and other units of measurement, people would use the tree's seeds to determine the weight of stones. One little seed was equivalent to the smallest gemstone at that time. So the weight of a gemstone was determined by the number of seeds.


Karat measures the purity of the metal and is most commonly used when referring to gold. The term Karat ranges from 1-24, where 24 is the purest. It is rare to see jewelry made of pure 24 Karat gold because gold is a softer metal and can easily be bent and scratched. Gold is often mixed with other metals such as nickel or copper to make it harder and more durable to wear. When a ring is 18K gold that means 18K of the 24K or 75% of the ring is pure gold and the other 10K or 25% is made up of other metals. The abbreviation for Karat is K or Kt.

A hand holding a piece of raw gold

Though Carat and Karat measure different things, Carat can also be used to describe the purity of gold, making the term interchangeable. Karat, on the other hand, can only be used when referring to the purity of gold. If you have any other questions about Carat or Karat, Steven's expert jewelers are ready to help!

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