There is a little test jig that is sometimes used,
that holds diagonal
corners of the die between centers, for a spin. If the die reverses
direction of rotation right before it settles to a stop, then it fails.
The 'Pviot test for loads'. There are several other ways to make dice
show numbers with the 'wrong' prboabiltiy, though.
Totakky OT, byut 'Scarne on Dice' has a couple of chapters on this. (No,
I don't gamble, but I happen to have said book on my bookshelf)
-tony