Argentium Silver Stacking Rings These stacking rings are made of 935 Argentium Silver for a longer lasting shine. Argentium Silver is 93.5% with a touch of Germanium that greatly resists tarnishing. Torch fused for an invisible seam, hammered, tumble hardened and polished to a bright finish. Each ring is a sturdy 16ga (1.3mm) thick. Four rings stacked together are approximately 5.5mm wide. Ring sizer included. Shipped in gift box.