The process of chemically darkening the surface of silver, creating a tarnish or patina, is a controlled acceleration of a natural reaction. This involves exposing the metal to compounds that react with the silver, forming silver sulfide on the surface. For example, immersion in a solution containing sulfur compounds will cause a darkening effect.
This controlled surface alteration is valued for aesthetic and practical reasons. It enhances the contrast of intricate designs, making them more visible and visually appealing. Historically, this technique has been used by artisans and jewelers to add depth and character to their creations. The resulting patina also offers a degree of protection against further, uneven tarnishing.