Indeed, the appearances were not the best guide for applying terminology.

You wrote:

"Regarding Chinese beads, I would agree that there is some confusion, but I wouldn't call it a "similar confusion." The bases of the beads in question are probably variable, and I don't know if they have been analyzed and qualified/classified comprehensively yet. However, I do know that they are sometimes characterized as being "ceramic" when an allusion or comparison to faience (that is, quartz paste materials) might be more apt. But the situation is complicated by the fact that many imitations of these beads ARE based upon ceramic constructions."

Some Chinese beads, attributed to Early Sarmatian period by persons much more knowledgeable than I, are described as having three layers: the obvious glass decoration on glass surface, then a layer of "terra cotta" over a material called "frit" but which would not properly be called that (as most likely not composed of sintered glass particles). Analysis of the inner two layers have not been published in these particular beads in some place I can get hold of the results. Maybe some day.

Best wishes,
Snap