Things You'll Need
Instructions
Plug in the portable UV counterfeit detection light and turn it on.
Place the questionable note or bill under the UV light.
If the note is counterfeit, the entire bill lights up brightly under the UV light. A high-end counterfeit detection light will give an audible warning sound when it detects a counterfeit bill.
Anti-counterfeit indicators become illuminated if the currency is authentic. You should see a bright, fluorescent, security strip on the left side of the bill. The $5 note glows blue, the $10 dollar note glows orange, the $20 glows green, the $50 bill glows yellow, and the $100 bill glows red. These colors can only be seen under the UV light. The different colors prevent counterfeiters from bleaching lower-denomination bills and re-printing them with higher values.
Check the note for an authentic watermark by holding it up to daylight, then check it under the UV lamp. The watermark on a real note will not be visible under the UV light, while counterfeit bills may show a poorly printed watermark.