In 1789 Martin Klaproth recognized Uranium as a chemical element and added it to glass as a colourant. However it took 50 years for this to become common place and only occurred when glassmakers in Bohemia, seeking new colours for a competitive market started to use it. Bohemia became part of the Austrian empire and the Napoleonic wars and glassmaking flourished.
The most striking aspect about Uranium glass is it is radioactive, a Geiger counter will give a positive reading. When uv light is shone onto it a fluorescent green glow is observed, although the levels of radiation are not thought to be harmful.
When added to glass, usually as an oxide a range of colours can be produced, from amber to apple green, depending on the mixtures used. If added to glass with a very high lead content a deep red colour is produced, although this is not commercially practical. During the early period uranium glass was usually heavy coloured crystal with facet cutting and polishing.
In the latter part of the 19th century some Uranium glass was produced using heat sensitive chemicals which when reheated turn milky white, producing the shading effects of Vaseline glass.
Uranium was a common source of yellow and green colouring for over 100 years, however in the 1940's it was banned as a glass constituent because it was used to make the atomic bomb. During the 1950's restrictions were lifted and some companies occasionally used uranium although the health fears dramatically reduced the number. The same colours can now be produced synthetically and very few pieces of uranium glass are made today.