Countries With Hard To ID Watermarks

Seigaku,

what about the Mexico Correos??

There are 2 vertically aligned like your types I, II and IV BUT only if you have the direction of paper vertically. And then it has a difference in height of the characters! 5mm id Samuel Jones, England, 6mm is Dennison, USA.... The 5mm version has a distance between the "o" that is higher than the "O'.... There is 1 type that has the horizontal alignement [direction of paper vertically!] like your type III.

But you haven't checked the mesh / direction of paper!

Horizontally aligned, slanted

That watermark is quite interesting! Thanks for posting it. I don't know any more than was published almost 50 years ago in Mexicana (full article is below, which links catalog numbers to watermark varieties), but as is the nature of Mexican philately, there are still a lot of discoveries to be made. Your possible Type V should be added to the list. I was trying to figure out what is on the face of your stamp--an Eagle Man?

South Africa triangles watermark(s) of the 1960s which comes 2 ways (SG) or as 2 different watermarks (Scott). You'd think they'd be separable by orientation but no such luck and can exist so light that they can be mistaken for unwatermarked.

British Commonwealth. Crown Agents 1970s spiral watermark and the later 1980s script spiral one. One of the papers used on the latter can make the watermark impossible to read.