I just received some certs from the PF and one of them was a big mystery to me. It's the second stamp in the image below. It came back as dark lilac. Perhaps that's the best match, but I can't find any dark lilacs in Siegel's records or in PF images that look anything like this color. I assume the PF has the best reference material, so I'm not questioning it, but I feel it is a pretty unusual shade. I read somewhere that there is a theory that the blackish violet and the dark lilac were probably made around the same time. So there you have it: a genuine dark lilac for your amusement. The other stamps are not certified - just there for comparison. I'd call the first one lilac, the third red lilac and the fourth some sort of gray.