Sterling Silver Turquoise Ring Size 6.5 Hallmarked RB

Three lovely pieces of turquoise in a sterling silver setting. Classic southwestern U.S. The ring is stamped sterling and hallmarked RB. According to Bille Hougart's book, Marks on Southwestern Silver, RB could be any of four people, so I'm unable to attribute any further. Condition is very good to excellent. The ring is size 6.5 and the top measures 1 9/16" x 3/4"