They are plain mandrel-wound lampworked beads with simple sparse millefiori, and have an obvious mandrel-release in the perforations.

All of these point to a probable Czech origin.

For all the reasons Jamey points out. They used to turn up in African trade strands, often with a yellow base. I liked the white base with simple blue murrine. I used to see whole strands of those. I’d bet Bully may have some in his stock…