Among several varying features (the slidelock screw, the battery cover, the supplied battery itself), the major one is the half-"5" in the tenths place on the fakes. On that basis alone he made the instantaneous judgement of "Chinese copy" for my caliper.
It is perhaps worth keeping in mind that this may not be a 100% reliable differentiator in the future. It seems plausible to me that as the counterfeiters recognize that the word is getting around, the design will mutate, and that what is already an excellent job of counterfeiting will become even more so.
-Marty-