The short white cylinders that have black trails on each end are Central European, and appear on sample cards. They were not, to my knowledge and memory, made at Venice. In point of fact, these are copies of German (Idar-Oberstein) banded agate beads; that themselves imitate more-ancient beads from Asian find-places. The original beads were probably made in India.

Viewing your necklace, I have to suspect it is more recent than you may be inclined to believe.

Be well. Jamey