Metals are either elements (shown in the Periodic Table) or alloys. The major precious metal elements are gold (Au), silver (Ag) and platinum (Pt). While jewelry can be made from each of these elements in its pure form, jewelry makers found they are not ideal choices for jewelry. Pure gold and pure silver are quite soft and malleable which causes them to scratch, dent, bend and break easily. These traits cause jewelry made from them to have a short lifespan. On the other hand, pure platinum is one of the strongest and most enduring metals in the world, but these properties make it difficult for jewelers to form platinum into jewelry pieces.
Because of the above issues, jewelers and engineers created alloys to make gold, silver and platinum a more practical choice for use in jewelry making. Alloys are elemental metals that have been mixed with one or more other metals or elements to take on new properties. The alloy is created to retain many of the positive characteristics of the pure precious metal, while reducing or eliminating key deficiencies. Gold alloys were created by mixing pure gold with a variety of other metals (mainly silver, copper, palladium, zinc, nickel and cobalt) for two primary reasons; 1) to make the gold harder and better able to withstand the rigors of jewelry wear and 2) to create new gold colors (white gold and rose gold, etc.)
Silver alloys were created by adding mostly copper and a few other metals to strengthen the metal and improve its durability. Platinum alloys were developed to make the metal more malleable and better able to be formed into jewelry pieces.