The main point of difference between the 18ct and 9ct Gold is the amount of pure Gold present in them. 18ct gold jewellery is comprised of 75% of pure gold and the remaining 25% is made up of other metals. In contrast 9ct gold jewellery contains 37.5% pure Gold and the remaining 62.5% of other metals. Another factor that differentiates 18ct gold from 9ct is the colour. As a result, the high proportion of pure gold in an18ct gold jewellery makes it more expensive than the 9ct gold jewellery. Click here for further information