Items made out of silver darken and lose their shine over time due to the mere exposure to bright sunlight, changes in humidity, contact with food, cosmetics, the human body and even air. That is why silver jewelry, silver cutlery and other silver items require repeated cleaning and polishing.
For silver not to darken or oxidize, it can be plated with a thin layer of rhodium. Since rhodium is nearly ten times more expensive than gold, and can be too brittle on its own, it is used as a finishing layer rather than the main metal in jewelry production. The rhodium finish gives silver their bright white color and prevents damage.
Rhodium is one of the most resistant metals to tarnish and corrosion. It is the brightest and the hardest within the platinum family. The brilliance of rhodium also enhances the magnificence of jewelry, while keeping its shine over time. And it is significantly less likely to cause allergic reactions than silver or nickel. These characteristics make rhodium plated jewelry increasingly popular.