tthe white and pink beads are shell chips

The dark gray beads with the silver clasp could be hematite (are they very heavy and cold?), or they could be plastic pearls, or they could be glass pearls...or maybe they're "real" pearls dyed black.
They are strung in the manner of pearls, with french wire protecting the cord near the clasp (which is a nice locking clasp), and knots between beads.
If you rub a "real" pearl (one grown in an oyster) against one of your front teeth, it will feel gritty; glass or plastic or stone will feel smooth.

Your green bangles might be bakelite (or some other plastic) or they could be dyed stone. Stone would feel heavy and cold - it you touch stone against your neck, it will make you shiver.