[Source] 3mm Coloured Glass Squares

Hi All,

a customer has come to me with a job that needs glass stones glued
in settings, hundreds of them. I can get round paste brilliants in
the right clours but it has little 3mm square by about 1mm thick,
green glass flats in it.

Does anyone know where I could get some, by the hundred. Preferably
in the UK but I would go elsewhere if necessary

in hope,