Some companies used a certain paper label. This type label was used by Aureliano Toso, I believe up until the early 1950s. Heiremanns has it pictured in his Themes book. The Loschs also have it at their signature site:
http://www.the-loschs.com/sigitaly.htm. The thing that I don't know is if A Toso is the only company that used this label. I think they are, but I am not sure.
A Toso did a lot of different things in the middle part of the century. I think that most of their everyday work was overshadowed by the major works of their lead designer, Dino Martens. I have run across a couple of bird paperweights recently by A Toso. They are nice, but rather unremarkable. If they had not had a label, I would have just considered them generic (in Murano terms this means no one knows who made them).
The reserve on the eBay weight must have been pretty high. I bid, but didn't reach it. I would have liked to have the weight for comparison, but not at too high of a price.

Chasing that elusive reserve...
Anita