Superdollar: the (Almost) Perfect Fake.

Superdollar: North Korea’s Almost Perfect Counterfeit. The superdollar is the name given to an almost perfect counterfeit of the US banknote, believed to be produced by North Korea in the late 1980s.

The superdollar notes were so good that even experts were fooled for years:

One defector who spoke to Panorama on the condition of anonymity said he had spent his life making counterfeit US dollars, adding that they were such good quality that they fooled experts.

He said: "The counterfeiting was all done at government level. We had a special plant for doing it.

"When I defected I brought some of these counterfeit notes to South Korea, and I showed them to the experts in the South Korean intelligence agency. They said - these are not fake notes. They’re real."

Link | Superdollar [wiki]