 The normal color of uranium glass ranges from yellow to green depending on the oxidation state and concentration of the metal ions, although this may be altered by the addition of other elements as glass colorants.Uranium glass also fluoresces bright green under ultraviolet light and can register above background radiation on a sufficiently sensitive Geiger counter, although most pieces of uranium glass are considered to be harmless and only negligibly radioactive.The most typical color of uranium glass is pale yellowish-green, which in the 1930s led to the nickname Vaseline glass based on a perceived resemblance to the appearance (which was a yellow-green color) of Vaseline brand petroleum jelly as formulated and commercially sold at that time.