Can you measure the perforations? All these Washington/Franklin types have several Scott numbers depending on watermark, perforation and printing. Having a perforation gauge narrows it down considerably.
I have two of these, but they are not the same Left one is 11 3/4 in perforation and it seems to have a watermark
According to Scott Catalog, the 5c blue Washington was issue in the following perforations:, 12x12, 11x11, 10x10, 12x10, so you may want to try those on your perforation gauge and see which one it is.
I would say it is Scott No. 504. But check here for more info: http://www.theswedishtiger.com/ID.html
