Submitted for your examination and comments. This is probably Scott 24, a 5 ore Ultra. But, that was difficult to determine based on the poor print quality and the cancellation. I thought at first it was 3 ore, but Retro Reveal did a great job in pulling out the denomination and some underlying features.
So, does this look like a heavily oxidized 5 ore? The NORGE is obviously Sans Serif font and I can't really tell if the post horn is shaded or not.
I'd say that you have unshaded post horn, meaning you have the 1882-93 issue. This means that the colour is in the grey-green range (there are a number of shades), not ultramarine / blue etc.
I managed to lose my copy of Facit 'before the storm' and haven't got a new one yet, so I can't tell you the dimensions of the two dies in this issue, which come in 'large' or 'small' sizes. My inclination is that you have the 'small' die because the value inscription is very neat.
Could be wrong but I see similarities (top right corner) , I was told it was "damaged" Hope it's helpful not hurtful.. I don't know anything about them! So I could be wrong and look like a dumb a$$ :) (If I am and there's nothing similar) Apologies
Sorry if my post wasn't clear(not the best at putting thought to paper) I just noticed the similarities in the colour change(might be possible all colours turn that brown) Not comparisons with the N :) And not saying it's not something special (just thoughts about the coulor) Also happy to bring up a old post and get some discussion going about it ;)
Got ya! sorry guys, thought I may have been offering some food for thought on colour options It was my understanding colour changlings are just damaged stamps in one way or another But I have much to learn