Hi, the lampworked beads in your necklace are quite similar to some of the beads in the Pietro Bigaglia sample book kept in the Glass Museum of Murano, dated about 1840-1860; some of them are also in the Giacomuzzi sample book (see Karl Karklins, 2002 "the Giacomuzzi bead sample book and folders" in Beads, Vol.14)dated about 1852-1868.
Ciao,
Giorgio