I have not (knowingly) seen the North Korean counterfeited supernotes, either the $50 or $100 denomination. However, in the last decade our own United States Bureau of Engraving and Printing has produced for collectors reproductions of valuable American postage stamps--the 1930's Graf Zepplins, the 1893 Columbian commemoratives, the 1898 Trans Mississippi issues, and so on; these are legitimate productions, of course, meant for collectors and printed intaglio from plates very close to if not identical to the issues they reproduce.
As one who possesses a few of the valuable orginials, I note that there is a slightly different feel between the new reproductions and the old originals. The new ones are "finer," perhaps in the way that the North Korean counterfeits are "finer" than the genuine American notes. The paper on which the reproductions is slightly harder. The ink does not sink into that paper--whose fibers are not arranged in the same way as those of the original, earlier stamps were--in the same way it did on the 1893 Columbians, 1898 Trans Mississippi issues, and so on. There is a new technique for examining paper fibers that may be to the point.
Has anyone with experience noted what I am saying? Can anyone out there speak authoritatively to these matters?
In my capacity as a publisher, I buy a fair amount of printing. I once was given in a bank a counterfeit $100 bill. Fortunately, I noticed it and reported it immediately; there was an FBI man present at that time who verified the fact. However, this counterfeit was an offset job; the face of the note (an older series one, with small portrait) was well done, but the back was to my eye quite sloppy. These new counterfeits would be interesting to examine. If there was a place (Bureau of Engraving Printing? Smithsonian?) I could look at one, I would like to. Is there one? If anyone knows anything specific and technical about the production of these notes I would also like to know that.
siwelregor