I think what I'm circling around and trying to lamely express is that I can see the Chinese making the brown beads as an export item, perhaps to Tibet (dzi) or Japan (ojime) or wherever, and then also adapting them for brush handles. The spindle shape just doesn't seem like something of use to the Chinese [awaiting enlightenment from someone with evidence on that score].

A contemporary example was the link showing "Murano" lampwork beads getting plugged into a brush handle - I very much doubt the traditional Chinese brush handle was the intended market, the beads are being made for export and fashion jewelry.

Also, what was the inspiration for the swirling brown hues? Some sort of rare wood? Amber? Agate? Why make opaque brown glass instead of something colorful and transparent? It just seems to be more to the Japanese taste rather than Chinese. But what do I know.