getting a little bit of a laugh here as this auction is from the very same person that Jimmy mentions a few pages back as a seller of Escher stones. Did you not notice that? =P
As an aside, i had a Mueller at one point, and it had some pyrite inclusions in it. i picked out the pyrite, and was able to get edges not so far from my vintage stones. (but not QUIET as good) I think the average honer would not notice. But the average honer probably wouldnt be picking pyrite out of a hone either.