Collect Radioactive Glass? collectors take a black light along with them to test Vaseline glass, also known as canary glass or uranium glass. Real uranium glass will glow green (old color of Vaseline) under a black light. Uranium was used as a coloring agent in the late 1700s up to the present day. That’s because the tiny amounts of radiation emitting from Vaseline glass are smaller than radiation emitted from many other things we encounter in our everyday lives.
This is called vaseline glass. It's got uranium in it to give it a yellow colour and so it glows under black light. It's a collector's item but you can often find inexpensive pieces on ebay under vaseline or uranium depression glass. It is NOT amber glass though, it is a much lighter shade of yellow than the amber depression glass. Just in case anyone wants to collect some for halloween or a party.