Napier silver tone necklace with blue beads

Very pretty and delicate with unique blue beads. The one in the middle that's hanging maybe missing its little diamond like chip. I'm really not sure. See last 3 pics above. The 2nd one is from the back of the piece. Also one of the beads on the side is missing one. It's shown in the last pic. Just want to be transparent. It's 16 inches long with an adjustable 2 inch extender.