Definetly no reject or factory canceled dice, All dice should have at least seen the inside of the casino they were made for.

Factory cancels:
Gold hotstamp "xx" on the 4
Gold hotstamp "O" on the four
A plain "VOID" stamped on the 4

Cancelations that are ok:(used by casinos)
Vicepunch (cuts small circle mark
Gold hotstamp wavey bar
Drilling
Scratching

A pinpric on the 4 side is used by both factory and casino, in this case factory cancels are often unfinished, will have machineing marks, or a raised logo (usualy gold)