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Hi. One approach to 'general' ID questions is to think about what is the frequency with which particular types of paperweights occur in the world, and in the country in which the item was found - and consider the most common sources first. I do not know the precise answer, but my guess is that commonest are Chinese, then Murano.
In the UK, somewhat less common than those two, but still numerous, are the Scottish paperweights (Caithness, Strathearn, Vasart, Perthshire, Deacons, Selkirk, Manson), pieces brought back from holiday such as Mdina/Mtarfa, and then the products of many smaller studios and makers (Langham, IoW, Liskeard, John Ditchfield, Okra, Island Studios, Avondale, Kerry, Adrian Sankey, Dartington etc). Less common still are Paul Ysart, Whitefriars, Old English, European antiques or American pieces.
What are always a challenge are the 'bubbles and swirls' type from small glass blowers who make just the odd paperweight, with either no signature or a vague scribble.
This is not the result of a detailed study, I hasten to add: more my experience of charity shops, car boot sales, and mixed lots at auction. Major auctions (and to some extent eBay) do not really give a representative cross-section, as some initial triage takes place before items are considered for sale.
Alan