Thanks to all for these very interesting and informative replies. I decided not to buy the bow. If the stick hadn't been soft in the middle I might have tried to bargain the price down a bit, but all told, too many problems with this bow. Shame, because I used to have a truly lovely Pfretzschner (early 20th century, silver mounted, fantastic legato sound, quite heavy) but it was stolen a few years ago and I still haven't gotten over it. Very interesting to see the link to the Pfretzschner expo catalogue, and also very interesting to see a photo of another "zebra slide" - I had no idea such a thing even existed!
I recently came across this unusual-looking cello bow stamped H R Pfretzschner and stamped with the Saxonian crest. The frog has an unusual "striped" aspect, and the slide has alternating bands of white (bone? ivory?) within the same wood as the rest of the frog. The tip plate is mostly gone. The pictures aren't great, I know, but what do you all think about this strange frog? Any idea if this could be a genuine Pfretzschner? I tried it out and found that it plays nicely - knowing of course that the balance will change once the tip plate is replaced - but the stick is somewhat soft in the middle. Is this a flaw that can be corrected by recambering? The stick is nice and straight, with no warping, cracks or flaws that I could detect with a magnifying glass. It's offered for sale at an antiques shop by someone who clearly knows nothing about bows or instruments, but knew enough to google "Pfretzschner" and slap a 2,500 euro price tag on it. I've bargained him down to 800 euros. What do you all think? Thanks for your replies!