OK, I'll bite.
what is a "Genuine ZK" ?
what is a fake ZK ?
Stephen
http://www.ebay.com/itm/ZORKI-ZK-1-...07110794?pt=Camera_Lenses&hash=item5643f1d98a
The above lens has a ZK name ring, but the mount and aperture ring are Jupiter-3 from later than 1951. No wings on the aperture, and the focus mechanism does not have the stop screw going through the focus ring. It is a Jupiter-3 with a ZK namering. Could the glass be older than the rest of the lens? Only way to tell is buy it and take it apart.
If it was the same price as a regular J-3, would be worth it. But the premium for a ZK- I would avoid this one.