Vintage Black Beads Necklace With 10K Clasp Gutta Percha? Vulcanite? Bog Wood?

VERY old necklace with unusual smooth, matt, black beads with a partial 10k gold clasp. I saw partial because I think one of the rings is not gold. . I tried to research this necklace without coming up with a real answer. Not sure if it is Gutta Percha, Vulcanite or Bog Wood or none of them.

It is lighter weight than glass and not cold to the touch. It has some indents in some of the beads and looks like the beads were molded because there are some lines going across the middles. It also shows some brown areas on the center bead.

In the beginning of each side of the necklace, it appears to be hand knotted, the rest of the necklace is not.

It measures 23" long and weighs 36.7 grams. Not sure if the clasp was an after thought? The string appears to be very old. Sold as is and as found.

If anyone can help identify these, let me know!