Craig:
Sorry about that link. I was having difficulty when I put the link on, and when I went back today it was impossible to navigate. They must be working on it. The price, if I remember correctly, was 240 euros.
I spent more time looking for Poli pieces and I think you're right about Poli also doing clear as well. That would have been nice way of determining attribution but it's a bit simplistic for Poli. I also checked the thread you mentioned, Great piece you have! Also, I was interested in Jerry's post, where he said that it was difficult to determine attributions for sommerso, as everybody copied everybody else. I was in Italy, including Murano, last October, and there's still a huge number of sommerso pieces being made by a multiplicity of furnaces. I think your approach of contacting several respected dealers is probably the most valid way to determine attribution, possibly even if it does have a label.
My apologies again.
David