Vintage Very Unusual Green Necklace

This is a very unusual necklace. I cannot find another necklace like it. It is VERY light weight. The necklace measures 28" long and the beads are approximately 3/4" across. No two beads are alike, so it appears to be artisan made?

The clasp is a screw style that has some greening and I don't think it is original to the piece. Sold as found.

If anyone knows what the beads are made of, please let me know.