I suspect it is possible that what is being thought of as the third aperture of a "T" perforation may be only a superficial broken bubble in the glass. WenP will have to tell us if this is the case.

The Boshan industry is the legacy of Japanese intruders during Occupation times instigating glass factories to make beads for export. I think that is or was a primary involvement. Not that beads were not used domestically. But more that their products should not be expected to predate the 20th C., nor to be included in pre-Communist arrangements. I have seen Boshan beads represented as "a hand rosary"—because there were 18 beads present. I think this was a conspiracy.

I will believe there are intact hand-rosaries of these beads when I see one. In the meantime, I don't think the present beads were so-used.

Jamey