An alloy is a mixture of two or more metals together to create both different colors and different purity levels of gold. For example, white gold is an alloy of gold, nickel, palladium and zinc. Rose gold is created by mixing gold and copper with silver. Because pure 24k gold is too soft to use in commercial jewelry, gold needs to be alloyed with metals such as zinc, silver and copper to make it stronger. The lower the karat weight of gold, the higher the content of metal additives in the alloy.
See Also: Gold, Zinc, Silver