That’s exactly what I did on mine. Read two posts up: Leia's Ceremonial Necklace: Prop Replica Collector OptionsIirc the closure is one element parted in two pieces. You could do the same and use small magnets on one side and a metal plate on the other side.
My comment was about the replica shown at celebration. I was wondering how they did their closure. I hope it is similar to the real prop as opposed to a simple snap clip.