A high resolution, say 600dpi, scan of the object will determine if it is genuine or not. We know exactly what the genuine looks like with the help of watermark's mouth-watering proof & other hi res scans on the net. How about these to make you drool & want to give up -
http://www.re-entries.com/pence_twelve_pence.htmlThe thick border around the item in question is not found on the genuine article. I don't need to be an expert on this issue to notice that.
In the case of paper, my Gibbons Red catalogue has 3 listings for the stamp. #4 on laid paper, #9a on thin wove paper & #14a on medium hard wove paper, the latter two only listed as used