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How Impurities Change Gold’s Color

The term “impurities” has many connotations, but in gold mining and refining, impurities refer to anything that lowers the karat weight or millesimal fineness of a sample of gold. In our business, we’ll accept practically any scraps or objects that contain gold, but we ONLY pay for the gold content – impurities mixed in or alloyed with the gold like iron or nickel end up as waste products of our refinery process. However, that doesn’t mean impurities are worthless!  
Impurities can be used to change gold’s physical properties (like hardness) or appearance. Just like mixing different kinds of paint to create new shades, mixing gold with other metals creates new colors. By adding “impurities” the creative jeweler or goldsmith gets to make a veritable rainbow of new colors that still have gold’s signature luster, weight, and value. For example, “white gold” is an alloy of gold and at least one white metal, such as nickel or palladium. In the infographic below, you can learn about the different shades of gold and what types of metal are used to create those colors.

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