There won't be any definitive batch numbers/ batch variation for these pigments as they were produced for a few years until they were discontinued in about 2003, so if she's looking in terms of identifying a fake any recent batch numbers are a giveaway, but anything with a batch code up to and including 2003 could be genuine.
Saying that, I've seen a lot of the fake original silvers about, and you can tell those from the colour, as the original silver frost was a dark, gunmetal colour, whereas the counterfeits tend to be more similar in colour to silver fog.