Etching is a method for adding complex and detailed patterns to metal using acid and acid resitant materials to create markings in silver. It allows you to create interesting effects and can be seen under transparent enamels. Variations on the technique can be used to create different effects.
Jennifer Stumpf combined metals combined etching and handstamping as well as metals in this piece
This pattern from paisley fabric etched into copper by Roslyn van der Wal shows how complex designs can be used