Salviati and Barovier (sometimes together) often had color inclusions in their early glass, so this wouldn't be unusual. I do have to say that I often am very hesitant about Venetian glass pieces such as this because they have been emulated so often. Some of their descendents are very good, so I have difficulty distinguishing. Perhaps Alex will be along soon to add an opinion on the age of the glass.
Someone sent me a picture of a similar piece for attribution in an email last night. Her piece was yellow with a serpent handle. But again there was deviation from the picture that I had of the Salviati & Co vessel. It can be very difficult to know if an object is a variation on a theme or if differences indicate a reproduction (or should I say, a piece that is inspired by something that came before).