K or karats is a term used to measure the purity of gold. In simple words, 24K gold is also called pure gold and has 99.9 per cent purity. It does not contain traces of other metals. On the other hand, 22K gold comprises 22 parts of gold mixed with two parts of other metals like copper and zinc. It is harder than 24K gold due to presence of other metals. It is suited for making jewellery.