Delftonic

Thank you again for your comment. I did get the sense, it could be an old forgery. 

Thank you so much for your reply. I will send you better pictures, with the mark. 

But given the drawings, I could understand if it were a forgery. 

I will try and upload better images.

Thank you so much for your answer. So out of the three plates this one is probably real Delft, and not a forgery, although you think the mark could be false.
I will try and put better photos this week.