Watermarks in the paper were for many years a stumbling-block to the counterfeiter, and practically all the old and generally poorly lithographed forgeries were on plain paper: nowadays, however, the watermark is imitated by actually thinning the paper where necessary, or by impressing it with a die cut to resemble the design, or by painting the "watermark" on the back with an oily composition which renders the paper slightly transparent, and so apparently thinner.
In a comparatively recent forgery of the Registration stamp of New South Wales sent by a correspondent, the counterfeit was produced by the same process (from line-engraved plates) as the original; the watermark showed very distinctly when the label was placed face down, but was not visible at all when held up to the light: it was a "paint" mark in a very faint tint of the ink used for printing that part of the forgery where it appeared.
Occasionally, but it must be admitted not very often, forgeries are so inscribed. A notable instance is the series of large handsome stamps issued by the United States during 1875-95 for payment of the postage on newspapers, singly or in bulk, and ranging from one cent to the high value of one hundred dollars: on each of these particular counterfeits the word "Falsch" was engraved as part of the design, and "Facsimile" was printed across the central portion of the stamp.
Practically the same course was adopted in the native manufacture of forged sets of the early Japanese stamps, the counterfeits (which were produced by the same process as the originals) being marked in the design with two microscopic characters signifying "facsimile": unfortunately for the honest intention of the forger to give due notice of the spuriousness of his productions, the incriminating letters are so small that a carefully applied postmark is apt to completely hide them.
Some stamps have been very extensively forged: for instance, of the 21/2 rappen issued in the Swiss Canton of Basle, in 1845, no less than seventeen distinct counterfeits have been detected. The stamp, of which an embossed dove carrying a letter in its beak is the central part of the design, is tricoloured—pale greenish blue, dull crimson and black—and, in common with most of the other Swiss Cantonals, is becoming rare. Copies have also been faked by thinning down card proofs of the genuine impression and adding gum.
Of the rarest Cantonal stamp, usually known as the "double Geneva," and consisting of two stamps of 5 centimes each, joined at the top by a long label inscribed with the aggregate value of 10 centimes, fifteen (probably more) forgeries are known; and as the entire stamp is priced at £75 unused and £28 used, it is naturally worth the counterfeiter's while to persist in the improvement of his imitations, with little hope, however, of attaining a perfection sufficient to defy discovery.
Individuals, however, are not the only forgers of postage-stamps: Governments, too, in their anxiety to provide so-called "reprints" for sale to dealers and collectors, have not hesitated to supply the necessary dies and plates, replacing those originally used and long since cancelled; and some have sunk so low as to deliberately manufacture counterfeits, and sell them as genuine stamps out of a supposed stock left on hand!
A reprint is an impression from the old original die, plate, or stone, taken after the stamp has become obsolete; but prints from a new die, however faithful a copy it may be, can only be correctly given one name—forgery.
In 1875, the United States Government, desiring to exhibit a complete series of their postage-stamps, and finding that the original dies and plates used for production of the Five and Ten Cents, 1847, were not available, ordered new dies to be cut: impressions from these, though closely approaching the originals, can be distinguished therefrom by certain minute but well-defined differences in the design.