Because of regular use and other factors, 925 Sterling Silver darkens. If it is acidic, there is a larger risk that the silver may oxidize and turn black. That explains why your jewelry tarnishes faster than other people's jewelry. The color of silver varies depending on its composition. Pure silver is very white and will sometimes include small amounts of other metals to change its color. For example, copper adds a red color and zinc adds a gray color to silver. But even with additions like these, silver still is very light sensitive and will darken over time if exposed to air and light particles. As silver oxidizes, it will turn from white to yellow, brown, or black. The rate at which this happens depends on many factors such as purity, type of metal used, how it was processed, etc. If you expose silver to air and light particles, it will naturally oxidize over time. This causes its color to change from white to yellow, brown, or black. However, if it is stored in a safe place away from the sun (out of sight, out of mind) then it should last for many years before it needs to be re-plated. Silver has been used for currency since the United States began using coins in 1792. Today, nearly all currency in the world is made of one form of silver or another.