Thanks for sharing, this is a beautiful piece. The stones appear to be pieces of stabilized Kingman Turquoise, and this would be Navajo made. The marking on the back is the end of STERL (ING) and is not the makers mark, so it is going to be very difficult to attribute this piece to an artist. The necklace has lots of turquoise and silver and would guess this piece to have a price around $900 to $1100 if you came across the necklace in a gallery. Hope this helps.