Help ID A Watermark/Stain - Great Britain KGV 1d - Sg 357

Hello, everyone.

I need some help. While examining the back of this stamp, I noticed a few different marks. At first glance, I classified this stamp as an SG 357 because the watermark is visible in daylight.

But here's my dilemma: in addition to the watermark I have identified as Royal Cypher (Simple), there seem to be two others, one in the lower left corner and one in the upper corner. It's most likely a result of the [1] number impression, but to the naked eye, the paper's texture looks a lot like a watermark, similar to a 0 with a hole on both corners.

Since my catalog doesn't mention this type of occurrence, I'm turning to this forum. My first question is, could it be a stain or would it be worthy study a bit more? Second, is there any mention of this type of occurrence in a specialized catalog, like two different watermarks? Third, could it be a forgery, or am I misidentifying the watermark? Lastly, to improve watermark identification, what do you suggest?

Comments?

Zé.

Those are from the edge of the sheet, where the manufacturer's watermark is.

You identified it correctly.
What you have is an interesting variety. It does not warrant a catalogue listing, but certainly is a good variety.




Almost correct: it is not the manufacturers watermark, That does not exist on British stamps. These are from column 12 in the sheet. The watermark has shifted to the left (actually, the sheet will have been misaligned or cut slightly incorrectly).
The watermark in the margin of the sheet reads 'POSTAGE'. Part of it is visible on OP's stamp.

Great information. Thank you Billsey and NSK.

Not an exact match but this shows the general idea:




[image borrowed from https://www.andrewglajer.co.uk/shop...cypher-html/]

That is a great one. With the letters of 'POSTAGE' being fully displaced onto the stamps, those are of catalogue quality.

Great, it really adds to the topic. By the way, I think I found another stamp with additional wmk but instead of 'POSTAGE' the stamp has lines with the watermark. It's a Australia SG 21 - KGV head. I'll show it in another topic.