Detecting Counterfeit Money, Part II: Color-shifting Numbers

(Note: This is the second of our four-part series on the common features of counterfeit money and the specific features that makes them easier to spot.)

This is a closeup of the most difficult printed security feature to replicate from the new US banknotes - the color-shifting ink used to print the numerals located in the corners on the front of the bill.

On a genuine $100 banknote, the green color will “shift” to grey and back to green as you tilt the bill back and forth to change the viewing angle.

  This next picture is from a counterfeit bill. While it may look the same as the previous one when viewed from a straight-on angle, the color will not change as you tilt and move it around.

The "optically variable ink", as it is officially called, is not widely commercially available. Most of it comes from a Swiss manufacturer SCIPA, which grants the U.S. exclusive rights to the green-and-black ink used for printing dollars. Nor can it be replicated by any copiers, which only "see" and replicate patterns from a fixed angle.

The next time you see a bill with numbers that do not change color, take note: more than likely, it is a fake.