Good ID site - findmetheoriginal.com  

I just stumbled upon this site. I did a search on DA to see if it had ever been mentioned and I couldn't find anything on it here.
I would have been immediately skeptical of it except that it's sponsored by Knoll, Vitra and the Republic of Fritz Hansen. They also have thirteen videos on Youtube. I watched the one on the Wassily chair; there is some interesting background on the chair plus they go over specific things on the chair to look for when determining authenticity.
Anyway, sorry if this is old news, but if it's not then I hope it'll be a helpful reference.
http://www.findmetheoriginal.com/