A huge high profile chunk of Chrysocolla from Michigan's Keewenaw Peninsula bezel set on a wide live cast birch bark cuff. All sterling silver.
 
Cuff is approximately 3/4" wide from top view.
Cuff band is 5.5" around with a 1.25" opening and is slightly adjustable.
 
DO NOT bend and open cuffs everytime you wear them - this will cause stress fracturing. Find a good size for your wrist and stick with it.