Vintage sterling silver poison ring

Adjustable. Opens and stays firmly closed. Stamped with “ sterling” and a makers mark on the back. The original ring is topped with mother of pearl or abalone, the black and silver top piece was glued on and can be removed, or wear it as is for a higher profile ring. The original top is still in place, you can see the edge of it in the last photo. Please note that the ring itself is sterling but the top piece that was glued on is not, it’s silvertone metal.