As you can tell by the hallmark, this is Mexican silver. What is interesting, was that I initially thought this was a more modern piece. But there is no .925 mark, rather, it is stamped “silver” which makes it a lot older than originally expected. I might place its age around the 1940’s or 1950’s solely based on the hallmark, not the style. The style appears to imitate Native American “Fred Harvey” style jewelry.
I am unsure of the stone, but it isn’t turquoise. from the pictures you provided, I would guess it’s an agate, jade or some other semi- precious stone that’s commonly used in Mexican jewelry. Better pics might help.
Thank you very much!!!