"Millefiori" is a 19th C. Italian word that is applied to any glass product derived from pictorial/image canes, divided into segments ("murrine"), and used cross-section-upermost to compose or decorate the object. If it's not cross-section-upermost, it's not "millefiori work," but rather just "mosaic-glass." There are lots of styles and types of mosaic-glasses.

In a general way, the name "millefiori" is used to encompass objecxts made as early as ca. 300 BCE (and even earlier) through modern times. The Venetians revived/reinvented this work in the mid-1800s, which is when the name was devised too. Of course, they also had a first reinvention of this work in the 15th C., when rosetta (chevron) beads were devised. But in the 19th C. very few people understood that this work had been pursued some 400 years earlier. The earliest Venetian products, millefiori and chevron beads, were both called "rosetta work."

I begin to understand your reply to my comment about your bead. However, a Roman bead that's not a Roman bead is sort of convoluted..., don't you think? If there are no Roman Period beads in sub-Saharan West Africa, it stands to reason that the beads recovered in Mali (and environs) are from later times. Most likley Islamic times. I would guess that this is what your bead most likely is.

I recommend the article I wrote on millefiori beadmaking for Ornament (1982), as well as a recent piece I composed for the newsletter of the Bead Society of Great Britain, from this past year.

Jamey