This is a "Gorakhnathi" necklace; the small pendant ending it -- which is perforated thorought --is not a mere adornment, but is supposed to be ritually used as a whistle morning and evening,to invoke the wearer's Guru.
They follow always a similar configuration, although the materials used are of course different. The elements on this particular one are: glass ring, red glass bead, rudraksha, brass whistle.