Enhanced security features, such as the 3-D ribbon and the color-changing bell and inkwell, help you detect an original 100 dollar bill. If you suspect a counterfeit bill, the U.S. Department of the Treasury requests that you get a good description of the person who gave you the counterfeit bill. Do not return the bill to the suspect, but surrender the bill to an identified police officer or Secret Service agent.
Verify that the blue ribbon is woven into the $100 bill -- not printed on it.
Move the bill up and down. Look at the ribbon and verify that the bells change to 100s.
Move the bill from side to side and verify that the bells and 100s on the blue ribbon move up and down.
Tilt the $100 bill and see if the bell changes from copper to green and disappears within the inkwell.
Look for the portrait watermark on the right front side of the bill.
Verify that the 100 in the bottom right on the front of the bill changes color when you move the bill.
Look for the security thread (the words "USA 100") that goes vertically through the left third of the bill.