Money check pen for quickly checking whether banknotes are genuine. Detects forged banknotes which are printed on starch-based paper. A clear or yellowish mark means that the banknote is genuine, while a brown to grey mark means the note may be a forgery. The mark will disappear on non-starch-based paper although a light-coloured mark may remain in some cases. For added security, a banknote testing device should also be used.