Here we have a 1947 Lone Ranger Atomic Bomb ring from Kix Cereal. 

The instructions stated that "you'll see brilliant flashes of light in the inky darkness inside the atom chamber. These frenzied vivid flashes are caused by the released energy of atoms. PERFECTLY SAFE - We guarantee you can wear the KIX Atomic "Bomb" Ring with complete safety. The atomic materials inside the ring are harmless."   Basically it was a tiny spinthariscope: when the red tail fin was taken off, you could look through the ring and observe some scintillations caused by nuclear reactions of polonium-alpha particles on a zinc sulfide screen. 

Nice looking ring, till you enlarge the pix a gazillion times, too bad it's missing the red cap.  Thanks for looking.