As near as I can tell, the a speo processes were developed at Venice in the late 16th century, and were adapted by the Dutch in the 17th century. No one can say, for sure, whether such beads (as we find in the trade from West Africa and North America) are Venetian or Dutch, because the Dutch makers were actually Venetians who imigrated, or they were trained by Venetians.

All of this was worked-out beginning over 20 years ago (in 1982 at The Glass Trade Bead Conference), and has been discussed many times. The best resource to read is Karlis Karklins paper in Beads, published shortly after my presentation at Bead Expo in 1994. I believe Karlis and I largely agree, down to most details.

I discourage reducing "a speo" to a popular bead name. The beads you are asking about are not "a speos." They are 17th century striped star beads, rounded by the a speo method. For short, "heat-rounded star beads." The dark blue ones, that lack a starry interior, are generally called "Dutch cane beads."

"A speo" means "on a spit." The other two similar names may be alternate choices, or may have specific (though now not understood) meanings. Originally, a cane segment was placed on a spit and inserted into a furnace, where heat softened the glass, allowing a rounded bead to result. This saved time and labor, in making it no longer necessary to CUT cane segments into rounded or non-cylindrical shapes, such as the typical chevron beads had (and continued to have). The cut star beads are called (in English) "chevron beads." Since the heat-rounded beads are not cut (to reveal internal layers), they are not "chevron beads."

The spit that was used was something like a skewer for barbecuing, and the process something like toasting marshmallows (to propose things many people will be familiar with). Since only one bead at a time could be processed, it was not very efficient. So the beadmakers developed a spit that divided into a group of separate ends (or you could say was many spits on a single handle), and they eventually made a post with a flat head, onto to which were welded many short pegs—and on each peg might go perhaps one to three or four cane segments. So, the process was refined to accomodate a greater number of beads to be heat-rounded at one time. (Though this was stil not nearly as efficient as the hot-tumbling of glass beads, that was effective for small canes but not lartger ones.) So, it may be that the three names I cite above refer to these evolutionary changes in the poroceedure(s), but it's not determined what's what.

I hope this helps. Jamey