Navajo from NE Arizona or NW New Mexico. This sounds a little weird but lick the stones, the old timers used to treat the turquoise w/ sheep or deer fat & if licked will stick to your skin. More modern silversmiths use stuff like shellac or linseed oil & it stays slick but does hold a sheen longer. I'm just guessing but think that's pre- 1960 & is worth a lot more than a lot of the modern stuff, some of which is nickel-silver or aluminum. Turquoise comes from several other places here in AZ besides Bisbee (Gleeson, Bagdad, Morenci, Copperopolis, etc.) but is all often called "Bisbee Turquoise".