Why do I consider this overprint one of the most difficult ones? The overprint alone has very few characteristics.
Just doing a large batch of Opinions. Its nice to see so much material at one place. Checking a single overprint with just the literature is a nearly impossible task. Once you have a collection with comparison items it gets easier. Useful are cancelled items where you can more easy get a feeling if the item is genuine. Also have a look at the backside of the stamp. If there are signatures you have even more details. Some signatures are a hint that the stamp and the overprint are genuine, some are a hint, the item is fake (e.g. the notorious “UZ”), some are no help whatsoever (“AG”). Now that you have items where you are sure the overprint is genuine and lot of items to check, make high resolution scans. I use 2400 dpi with is quite much and you need a scanner, that was not the cheapest one at the market…
Here are the details of “different” overprints of the “3”. What do you think: are all the same?
The rounded nature of the left one leads me to believe it might not be authentic (but then again, I am very new to this).
Here’s a scan of mine, this is THE stamp that was featured on your STOLOW/Ebay blog.
In my Forgery Guide No.16 I list three genuine types, two quite rare Type 44 and Type 44x (using T &A nomenclature) and Type 46. The third from the left of the 4 illustrations is I believe Type 46 as it largely meets my criteria (on page 6). I list and illustrate three forgeries, F1(3), F2(3) and F3(3) at 24,000 dpi and these differ from the other three illustrations which I will call F4(3). F5(3) and F6(3) in any future reprint of Forgery Guide No. 16.
One more try for the link 🙂
Yes, that one looks nice too 🙂