Having had a variety of comments so far, from a variety of collectors, there seem to be two definite conclusions - 1. It's not a Clichy weight, 2. Nobody is 100% certain of what this one really is.
Amongst those offering views was Marek Kordasiewicz, author of the book, Sklane Przyciski Do Papieru ... (Glass Paperweights, The Heritage of The 19th Century Riesengebirge and Isegebirge Glassworks).
Marek says that we should not pay too much attention to general shapes and profiles when considering "Bohemian / Silesian" weights. He has seen almost all profiles in these.
Also, he has seen only a few weights like Nadine's (through eBay, sold from India!) but has found none at all in Poland, and therefore thinks they may have been export pieces. However, he does have a "classic period" (19th century) Silesian weight that has a simiar base, with "a very deep concavity". And he comments that some of the canes are similar to ones he excavated in the Carlsthal glassworks area.
Without checking technical details such as Spefic Gravity and UV reaction, a truly positive Id cannot be given, but on balance, Marek's opinion is "Bohemian or Silesian origin".
When I checked Marek's book for cane types, I could not find any exact matches but it was clear that there were many Bohemian / Silesian canes formed with a single cane surrounded by multiple individual canes. It was that style of cane, and the overall layout that made me first think of Bohemian. But without a positive cane match (and preferably more than one), I think it would be useful to look around for other weights like the mystery piece.
If this weight could be seen at the next PCC meeting, I will happily check it under UV.