Check For Fake Dice, July 1945
For the gambler who suspects he may be more than just unlucky, in 1945 we offered a couple helpful tips for seeing if those dice are up to snuff. If you make a stack of three and the suspected die can't slide in the middle slot, you might have a fake on your hands. If that's not an option, grab a bucket of water and see if one side immediately sinks to the bottom.
From the article "Why Dice Behave As They Do."