Karat (abbreviated Kt or K) is a measure of the fineness or purity of gold. 24 karat gold is pure gold. 18 karat gold is 18/24 gold (about three quarters gold). 14 karat gold is 14/24 gold (a bit over half gold). 12 karat gold is exactly half gold. 10 karat gold is 10/24 gold. Pure gold is very soft, so it is often mixed with other metals to give it hardness and strength. This mixture of metals is called an 'alloy'. 'Karat' and 'carat' do not mean the same thing. A carat is a measure of gemstone weight and does not refer to gold.
Karat - Definition 
