Southwestern Style Serpentine (?) Stone And Silver-tone Ring, Sz 10.5

Beautiful large stone, Serpentine or similar agate, from what I can tell. Tones of green, white, gray. Silver metal does not react to magnet and could be sterling, but not marked. Braiding detail is separate piece from setting and there are small spaces in between, all the way around - it was made that way. Unisex style. Stone measures approx 1.25" x 0.5". Size 10.5.