A bead necklace in nephrite is graded as it is strung: beads are sorted for colour and size so the strand runs evenly, which is harder with jade than with a uniform stone because each bead came from a different part of a block.
The clasp is a sterling silver lobster, stamped S925. Nephrite is one of only two minerals properly called jade; the colour here is the natural green-to-white range with the variation that identifies untreated material.