The Sharpie® counterfeit detector pens (also known as counterfeit detector markers or security pens) are trusted detection against counterfeited fake bills. These pens are known across many industries for reliable detection and for containing specially formulated ink which indicates a yellow mark on genuine bills, and a dark mark on counterfeits.
Simply write on any stand U.S. currency to detect a counterfeit bills
A yellow or light colored mark indicates that the bill passes the test
A brown or darker colored mark indicates that the currency fails the test and may be counterfeit
For best results, judge the applied mark immediately after application