The black-on-silver Venetian Glass - Castle Murano foil label was one not familiar to me, but researching it further, I discovered that it was frequently associated with the work of Fratelli Toso. A closer inspection of the round label on the underside confirms that it is a mostly worn Murano Glass - Made in Italy blue on silver metallic label used by Fratelli Toso.

This paperweight measures 3-1/2" in diameter and approx. 2-3/4" high, with a weight of 1-3/4 lb. In near excellent condition, with a couple of superficial tooling marks and a short scratch up by the leaf that do not detract.