In The Evil Dead, Ash gives his girlfriend Linda a necklace prior to the first deadite incident in the cabin. At the end of the movie he used Linda's necklace to grab the Necronomicon Ex Mortis while he was pinned down by the deadites of his friends. In Evil Dead II, it causes the deadite Ash to remember his friends and how much pain the deadites had given him, turning Ash back to normal.
The necklace was purchased from a Michigan jewelry store called Corey's Jewel Box. It is silver with a small magnifying glass inset. During production, the original was misplaced and a gold substitute painted silver had to be used. In Raimi's originally conceived idea for the climax of the film the magnifying glass portion of the necklace catching the light of the rising sun would have made Ash realize he needed to burn the Necronomicon.
In Evil Dead (remake) David gives his sister Mia a wooden charm necklace that looks suspiciously like the one Ash gave Linda. The charm does not serve any of the characters a practical purpose, however.