I make my captive bead designs out of Argentium sterling silver using sheet and wire. It's a nickel-free sterling silver alloy that has increased tarnish-resistance, as well as better durability and scratch-resistance over traditional sterling silver.This is the manufacturer's FAQ page on Argentium silver if you would like to learn more: Silver FAQThis is the technical information sheet for the silver I use that shows the alloy composition (96.2% silver, copper, germanium): Argentium 960 Technical Info Sheet