This is a dramatic and exquisite vintage Navajo squash blossom necklace.  It has seven Royston squash on either side and four Royston stones in the naja.  It also has three silver bead strands which makes this squash blossom stand out among other necklaces.  It measures 16″ long and is a medium heavy piece.  However, it wears very comfortably because it is flat and smooth on the back side.  It is unmarked but my best guess would be it was made in the 1970s.