Shell, Akro, Vitro, Master, Marble King, Alley and/or Champion, and foreign companies have all made clearies. It's nearly impossible to tell whose those might be.
One way that you can sometimes narrow your guesses down is to look for their cutlines or to look at them under a blacklight. Sometimes you'll get hints about the structure which make one company stand out as a more likely guess than others. But it's practically impossible to be sure unless you have them in the original packaging, so the main thing to do with clearies is just to enjoy them for the colors and light effects.