I don't know how you can tell if a pigment is a fake, but I think that's just the batch number. I think that's on pretty much all of their products now. Someone correct me if I'm wrong!
It shouldn't be. All the pigments have numbers to indicate the batch it was produced in. You can check the precautions page to find out how the number system works. http://www.precautions.specktra.net/
like stated above the pigments all have batch numbers under the names if its a tester it will say (sample) or (wn) for working name, glitters although do not have batch numbers.