Nomadr,
The photos that Leon made available are excellent examples of genuine BW grips as Ron Wood has stated...
While this is mere speculation... Luke Smithwick and I have been studying BW grips for a couple of years, and in all the examples that I have seen of genuine BW grips, the small circular marks, easily apparent in Leon's photograph on the small "islands" on the back of the grip that hold it in position when mounted on the gun, (see the photo enlargement of one of Leon's photos)
are so consistent that if you cut and paste portions of the photos of this area and overlay a photo from a genuine grip that these circles will match, much like the striations on a bullet from the rifling of the same gun. While some producers of BW reproduction grips could try to attempt to put these circular machine marks on their grips so they would pass as genuine, this is such fine detail that it would most likely not be cost effective... and they would never really line up if compared with a genuine grip.
This fact leads me to conclude (correctly or otherwise...) that ALL genuine BW grips may have come out of the exact same mold... I know that is far leap considering just how many grips must have been produced, but I don't know how else to interpret the findings... The genuine grips were only used for a short time of production, but I don't think any information has surfaced that identifies exactly where these grips were produced, or how long the production cycle may have been before they started installing them at Mauser.
But now, for the other side of the coin... May I request that you should definitely post the photographs you received from the seller, in what ever detail they provide, so that others may see the genre of the imitation, and can avoid them in the future...if you need assistance in posting them, just let me know, I will be glad to help.
...and G.W., you are also correct... this forum is the absolute finest of it's kind... we seek the truth for all to share.