A black obsidian mala is the plainest version of the form: 108 beads with no colour variation at all, since obsidian is glass rather than a crystalline stone and there is no internal structure to produce grain.
Because there is nothing to distract the eye, the shape has to carry it, and each bead here is polished to a round with a fairly tight tolerance. Marker beads at the quarters and a small brass guru bead. Obsidian will chip if it lands on tile, so mind where it is set down.