I note an error in my posting of 25th Jan. Uranyl is UO2 2+, not UO" 2-. The fluorescence of uranium in glass is limited to the +6 oxidation state, of which UO2 2+ has the most intense fluorescence. The first time I saw uranium glass at an antiques fair I didn't know what it was, but its colour reminded me of Zinc Uranyl Nitrate, a chemical that I had used in chemical analysis. I took it home and tested it with my Giger counter, which gave a very strong clicking. That started my rather large collection! I also have quite a lot of uranium pottery, which is much more radioactive than the glass is.
Moultermike