I knew what you meant, I have a Michel, and my collection separates wmk 5 and wmk 6. I know that wmk 3(135 circles) has a 4 point star and VI (paper makers mark) 4 times per sheet. I have a 12 f postage due wmk 4, perf 11.5(scott 15a) Unused that clearly shows a VI in the space between 4 of the crowns. I have not heard mention of VI being on any other watermark except wmk3. This is not the best picture, but you can clearly see it.
Any idea what this is? The only one like it I have seen in the thousands of 136a stamps I have. Thanks for those images by the way.
The paper grade watermark, which was IV for postage stamps, was used on stamps with crown watermarks between 1899 and 1908. Up to 1904, when the cross on the crown was (incorrectly) titled to the right, you would see IV, otherwise you would see VI. After that, IV is shown when cross is correctly tilted left.
On the small crown WM (136a) the IV/VI appeared once per sheet of 400 stamps, so its rarer than in the circle/oval WMs of previous issues. Not all sheets will have the IV/VI if it occurred on the edge of the paper sheet.
Thank you Lewis! This is the first one I have found, but now will keep my eyes out for more. It's amazing that this is not mentioned anywhere. Where did you find this info?
This image from the MBA catalog was provided by Csaba Kohalmi from the Society for Hungarian Philately. Now I need to look for one with the IV diamond.