A wonderful necklace of graduated millefiori! Is it possibly an original mount? I have the one in the picture in my collection: it is a proof by Moretti from the '30s, without a clasp. They didn't normally sell mounted necklaces, and this can be a proof to see how their beads worked; possibly somebody else realized the final mount like your, or used the same model. What I like of this millefiori, intended for the western market, is that they (to me)represent the peak in quality of Venetian millefiori production, due both to the skills of beadworkers (women) and to the quality of the millefiori canes.
Giorgio