What’s the difference between 14 karat and 18 karat gold? Why is higher karat gold darker in color, heavier, and more valuable? It all comes down to gold content and purity. The higher the karat the higher the gold content. Jewelers take 24k or “pure” gold and add alloy metal to change the purity of the gold. For example, 14 karat is 58.5% gold with the remaining 41.5% alloy metal. Understanding the purity of gold will help a great deal when buying or selling gold jewelry. Check out this guide for more in-depth info.