Looking at your close up pics make me indeed think they are not glass. My clued are the white edges around the hole. They are not consistent with glass and appear to be the result of drilling. Also, the pattern looks like it was not lampworked.
Could it be 'block turquoise'? It is generally a mix of resin, dyes, something to form the matrix and other chemicals. It can feel quite stone-like, but there is no actual turquoise in there. It is made in blocks from which beads and other things are cut. There is also reconstituted turquoise which does use (some) actual turquoise mixed with resins.
I have not seen any graduated bead sets made from this material before, block or reconstituted. But it certainly would be possible.