Hi,
I thought better about my response.
The pieces in this shape I've had with Seguso labels are all one color, with another color over them (sommerso). I would guess that other companies, such as Barbini, did similar items, and that as yours fades in color from bottom to top it might be by someone other than Seguso..
I think it's fair to say that Poli is out. I've never seen anthing like this with a Seguso Vetri d'Arte label. Does Pina give any sources for her attribution?
Laura