http://pfsearch.org/pfsearch/pf_grd...tFirst=First;
Note that there are only 15 used singles certified by the PF for the years they have posted online so far - which I think is back to c.1980 or so, which is 34 years. It is interesting too, to see the number of FAKES with seemingly-large margins which would be convincing to most. Also interesting to see how many they "decline opinion" whether or not the CANCEL is genuine or not. Also note the FAKES that do have the "lazy eye"!
Also interestingly I just yesterday certified a too-small used single copy as being genuine, only because it came from a certified PAIR which was cut up so that the one copy, which had very large margins could be sold at a big price. It only measured 20X23mm, generally WAY too small to be considered genuine, but because it was cut from a pair, it is indisputably good. I would guess there are less than 50 certified genuine used #315 singles in existence, so buying an uncertified copy is going to virtually always be a waste of time, energy, and possibly money.