Vintage Black Crystal Glass Graduated Necklace

This vintage necklace features graduated black faceted crystal glass beads individually knotted. The thread has come untied at the clasp but is still secure. The approximate length of the necklace is 17 1/2" and the closure is a spring clasp. My sister-in-law was an avid collector of so many things, jewelry was just one category. She knew everything about each and every one of her pieces but unfortunately she is no longer able to tell us. I'm not an expert - I just offered to help find new homes for her beloved pieces. This is a vintage piece and has evidence of wear that is appropriate for its age. Please examine all photos closely for condition.