The main difference between 916 and 999 gold is their purity levels. 916 gold, also known as 22 karat gold, is made up of 91.6% pure gold and 8.4% other metals. 916 gold is commonly used for crafting everyday pieces of fine gold jewellery. 999 gold, known as 24 karat gold, is the purest form of gold available. As such, it is softer and malleable, which means that fine craftsmanship is required to fashion it into fine gold jewellery. It is often used for exquisite pieces like in Si Dian Jin.