The 24-karat gold is the purest form of gold which contains 99.99% of pure gold. There is no other higher form of gold other than 24K gold. It is only used for investment purposes because it is a very soft metal. On the other hand, 22-karat gold is 91.67% pure gold mixed with other metals to make it harder. Thus, it is suitable for jewellery making.  Read more Difference Between 24k and 22k Gold