Hi Christine
Perhaps uranium is the wrong ingredient, the post was late last night - the bowls (the green one more) have a thick glass base that is not clear but slightly fluorescent (only word I can think of) - the rest of the bowl is made of the same glass and over and above the pattern colours in good light gives off a blue haze that seems at first more than mere opalescence or iridisation - it may be just that - I don't have a UV tester so cannot check in that manner.
Adam P