One of my necklaces was looking tired, with the "silver tone" findings starting to tarnish. It was really simple to fix this.
*Some 1mm black, waxed, cotton cord (which was cheap as chips)
*2 x 6mm sterling silver beads, with a 1.3mm hole. The beads were from Benjamins Crafts.
*Sewing scissors to trim the cord
-Carefully cut apart your old necklace.
-Take your cord, and leaving a long "tail" tie your first knot, then start threading your beads on, pushing a half reef-knot right up to each bead.
-Put another knot right after the last bead, leave another long section.
-Put a knot, about an inch and a half from each end.
-Thread on your silver beads, and secure with one more knot.
-Trim ends if needed.This worked well, and you just wear the necklace with a little bow :)