From The Postage Stamps of J&K Simplified by Dawson & Smythies, p 20.
The Jammu rectangular stamps were also reprinted in old colours on native paper only, but these reprints are anything but common, and thus very different from the circular reprints. They can be distinguished from originals by being extremely clearly printed. The brown-red shade is distinctive, and these are the varieties usually met with, the vermilion and blues being rarer, and only one specimen of the bluish-green is known.
Only one type of forgery of the Jammu rectangulars is known; it is a scarce to rare single die watercolour imitation of the ½a, aparently made to defraud the Post Office. It is easily detected by its having a thick outerframe line all round, whereas genuine stamps can have frames on two adjacent sides only; it is in one type instead of three types, and the sun at the top of the oval has truncated instead of pointed rays.
It usually appears in a deep carmine-red, with the square black Jammu seal, but even this may be forged as it generally looks too lightly applied and clear to be genuine. It is also found with the circular magenta seal. These forgeries exist also in the ½a black and the ½a blue [and may be seen on the main site, ed.]