I hate to disagree with my friend Paul, but the 1930s filigrana pieces I've seen are thinner and lighte than this. Furthermore, the eaerlier filigranas were not cased in clear. I agree it could be Salviati (or Fratelli Toso, or many other companies), but I'd place it in the 1950s, when thicker glass was the norm and almost everything was cased in clear.
Laura