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How much gold is contained in 18-karat jewelry?

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A diagram showing the periodic table entry for gold, with the symbol Au, atomic number 79, atomic weight 196.96657, electron configuration, and labels for its properties as a solid transition metal with a face-centered cubic crystal structure. — gold The precious metal gold is a chemical element with the symbol Au. Its square on the periodic table details some of its properties, including its atomic weight, atomic number, and crystal structure.

In 18-karat gold jewelry, the gold content is 75 percent by weight.12

The karat system measures the purity of gold alloys, where 24 karats represents pure gold. Because each karat is equal to approximately 4.167 percent of the total composition, 18-karat gold is calculated as 18 multiplied by 4.167, resulting in 75 percent gold content. The remaining 25 percent of the alloy typically consists of other metals, such as silver or copper, which are added to provide the necessary hardness and strength for jewelry production.3142