Straight from a 1950s Sci Fi movie!!
Uranium glass is a collectible antique glass that was made with uranium salts. Uranium salts are naturally a bright yellow and they were used to color the glass. Uranium glass ranges from yellow to green, with the green versions having had additional coloring chemicals added. Uranium glass is transparent to opaque and comes in many forms and styles, including plates, glasses, cups and saucers, salt and pepper shakers, candlestick holders and figurines.
As it contains uranium, the glass is radioactive. Happily, the uranium salts added and radiation given off is so low it’s considered harmless.
Uranium glass is identified by its general appearance and color (yellow to green) and because the uranium salts makes it fluoresce a bright green under black light. Some advanced collectors and dealers even use a geiger counter to measure the radiation, but for most people a black light is more than enough.
There are sub categories for uranium glass. The problem is different people use the names differently, even sometimes applying them to non-uranium glass that has same superficial appearance. Some areas of the world use the terms differently.
The following are common subcategories.
Vaseline glass is a nickname given to uranium glass that is transparent and with a yellow or yellow-green tinge. It got its nickname as some thought it resembled vaseline. However, some call any kind of uranium glass vaseline glass, some say vaseline glass can only be yellow and some call any kind of transparent yellow glass vaseline glass even if there is no uranium salt content. Some collectors and dealers label that syrup pitcher vaseline glass, while others would not because it’s not yellow. The latter would call it simply uranium glass.
Custard glass is a uranium glass that is an opaque or near opaque yellow. Though some some call any opaque yellow glass custard glass, even if it contains no uranium.
Jadite glass is uranium glass that is opaque or semi opaque pale green. However, some call any opaque or semi opaque pale green glass jadite glass even when it has no uranium content.
With all the competing subcategory definitions, just remember that a black light will tell you if something has uranium salts in it and is genuine uranium glass.