The 1" Marbles are hand made and each is unique with pontil marks. I was told these were prototypes for a Glow in the Dark game back in the 60's that never made it to production.
LOL, I love how companies make up stories to cover up low quality products. All the Uranium marbles being sold lately are crap quality. Air bubbles, nicks, and off axis. If you look at really old marbles the quality if far superior. From what I've gathered is (opinion not facts) they are factory rejects. Or a company had some left over glass, and pumped these out before the ban on Uranium glass took effect. Who knows really, but they were not made for some old game.