Navajo Turquoise Ring in Sterling Silver TSO Size 8

Signed Navajo sterling silver set with a genuine turquoise stone with some brown matrix. Size 8. Face of the ring measures 1 1/2" long. Weight: 10 grams. Some tarnish. Nice condition. 

This ring was made by one of the Navajo TSO family. It is hallmarked on the back, but the hallmark is not clearly stamped so I can only read TSO and several members of this family used this script stamp.