Danny, I have practically a litter-mate to yours, part of an assortment of lovely small grinds that were my holiday bead-swap gift from Alan last year. So I'd bet good money it's vintage Italian cane, but don't know the maker...

Spoke with Thomas regarding this bead yesterday and he pretty much cleared things up for me.

This bead is a chevron that was put in an optical mold that never got the last outer layer of glass or the outer layer released when it was pulled. Seems right to me.

About 1988. It was just pulled without a final unmolded case. The one I pulled was light purple and was troublesome to finish out. The ribs chip easily when they clunk around on other beads. In those days I ground all the beads off of a cane in one cycle so I kept the beads separated in egg cartons so they wouldn't chip each other while I was doing all the processing. Only about 20 beads off of that particular cane.