Carat vs Karat - what's the difference?

Published by Gordon Weller GIA GG on 4th Nov 2016

The term “carat” (abbreviated ct.) is associated with gemstones. The term karat (abbreviated K or kt.) is associated with the amount of pure gold in a gold alloy .

A carat is strictly a measure of weight of gemstones and is based on the metric systemOne carat equals 0.2 grams. This means there are 5 carats to a gram.


So, when you spring for that 5 carat diamond you’ve always wanted, you’re really getting a diamond that weighs 1 gram. Carat weight is one of the 4 value factors in the GIA diamond grading system. The others are color, clarity and cut.

Karat communicates the amount of pure gold by mass in the gold alloy used to make your gold jewelry. 


Pure gold is assigned a value of 24 karats. It's 100% (24/24ths) gold with no other metals mixed in. When other metals are mixed in to create gold alloys, the ratios of gold and other metals become:

18 karat gold is 75% (18/24ths) pure gold and 25% (6/24ths) other metal alloys.

14 karat gold is 58.3% (14/24ths) pure gold and 41.7% (10/24ths) other metal alloys.

10 karat gold is 41.7% (10/24ths) pure gold and 58.3% (14/24ths) other metal alloys.

Mixing in other metals to create an alloy reduces the gold content of the finished metal, but increases its durability and strength. 

At 100 East Fine Jewelry, you can shop by Gold Karat Weight, as we have conveniently organized our website by 18K gold jewelry and 14K gold jewelry