Firefly Jewelry Necklaces are 16 (17' w, extension) unless otherwise noted. The necklaces are either made with silk thread, antiqued steel or antiqued brass chain. The findings used in the jewelry are brass that has been silver plated and then antiqued. .Firefly is privileged to integrate the world's finest crystal into their designs: Swarovski. The Firefly Jewelry company has a deep love of color. And Swarovski Elements precision cut crystal comes in such a wide palette of innovative colors that it inspires Firefly's imagination when planning out new designs.