Mostly the two words ‘Carat’ and ‘Karat’ are confused to be the same. First I would like to clarify the difference between ‘Carat’ and ‘Karat’. Karat- It is a unit to measure the purity of gold. Where 24 Karat or 24k is purest form of gold. Carat- It is used to measure weight of gem or precious stones. It is a unit of mass where one carat is equal to 200 mg (1 carat = 200 milligrams).