The Chinese imitation zi, as I attempted to explain, have not been the subjects of much scrutiny. Consequently we only have the suggestion that they might be Chinese (by Beck—unchallenged), and the circumstantial knowledge that the bead Beck showed was presumably "old" when he published it in 1933.

Serpentine is much softer than agate (which is medium-hard, but not as hard as precious stones). You will use a sharp pointed knife or a sharp Xacto knife. (I use any blades in my Swiss Army knife; or a sharp pointed Xacto.). A steel knife or blade will not scratch quartz (including agate)—which is the most-common mineral beadmaking material in the world. But it easily scratches serpentine. Apply the POINT of the knife or blade, in an inconspicuous place (near the aperture is good), and rotate it—like you are trying to dig a tiny round hole. You can turn it back-&-forth, or in a circular turn on its axis. You will not be able to have any impact on quartz. But serpentine will give-way easily. You could try to actually scratch the surface, but this makes a bigger more-obvious mark. Digging is just as effective and a much smaller mar.

By the way, all the above also holds true for actual jade (nephrite and jadeite) in comparison to other false jades (many being serpentine) that are softer than jades. See previous discussions for good advice about jades and "yu."

I did see your impressive long white bead! Ancient drilling is marvelous—in the sense of actually being a marvel. Contact me privately if you want me to take a closer look. jamey4beads@gmail.com

Jamey