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The short answer
Check a current $100 note in four steps: tilt it to see the blue 3-D ribbon's bells change to 100s and the bell in the copper inkwell turn green; hold it to light to see the Franklin watermark and the security thread; and feel the raised printing on Franklin's shoulder. Do not rely on a counterfeit pen, which the US Secret Service has warned can be passed by altered notes.
Why $100 notes are the ones to check
Dollar cash still changes hands in Nigeria for school fees abroad, travel, savings at home and trade. The $100 note is the most common denomination in those deals and the one most worth counterfeiting. Buying from a stranger, receiving a bundle as payment, or changing money in a hurry on the street are the moments when fakes are passed.
The checks below are taken from uscurrency.gov, the US government's official currency education site, for the $100 design issued from 2013. Older designs also exist; if you are given an older-style note, compare it with the matching design on the same site rather than with these features.
The security features, one by one
Tilt the note
- 3-D security ribbon. The blue ribbon on the front is woven into the paper, not printed. Tilt the note back and forth: the bells on the ribbon change into 100s as they move.
- Bell in the inkwell. Next to the ribbon is a copper inkwell with a bell inside. Tilt it and the bell changes from copper to green, so it seems to appear and disappear.
- Colour-shifting 100. The numeral 100 in the lower right corner of the front shifts from copper to green when tilted.
Hold it to the light
- Portrait watermark. In the blank space to the right of the portrait, a faint image of Benjamin Franklin appears, visible from both sides.
- Security thread. To the left of the portrait is an embedded thread printed with USA and 100 alternating. Under ultraviolet light, the thread glows pink.
Feel and look closely
- Raised printing. Run your finger over Franklin's shoulder on the left of the note. It should feel rough. Raised printing is used throughout.
- Microprinting. Tiny text appears on Franklin's collar ('THE UNITED STATES OF AMERICA'), along the golden quill ('ONE HUNDRED USA') and as small 100s in the borders. Magnification may be needed.
- Large gold 100 on the back. It helps people with visual impairment identify the note; it is a design aid rather than an anti-counterfeiting feature.
The pen-test myth
Many traders swipe a counterfeit detection pen across a note and accept it if no dark mark appears. The pen reacts with starch in wood-based paper; genuine US notes use a fibre-based paper, so no stain forms. The weakness is that a genuine low-value note can be bleached and reprinted as a $100. A US Secret Service official told the Saipan Tribune in 2012 that an altered $5 note can pass a pen test, and that a fake with the wrong watermark, Lincoln rather than Franklin, 'will pass the pen test 100 percent of the time'. He advised checking the portrait, watermark, security thread, microprinting and colour-shifting ink, and suggested a handheld black light.
That bleached-note trick is exactly why the watermark check matters: if the faint portrait in the window does not match the face on the note, it is not a real $100.
A quick routine for every note
- Count the notes in good light, away from distractions or a crowd.
- Tilt each $100: ribbon bells to 100s, inkwell bell copper to green, corner 100 copper to green.
- Hold each to the light: Franklin watermark on the right, thread on the left reading USA and 100.
- Feel the shoulder for raised print.
- If you have a UV torch, check the thread glows pink.
- Put aside any note that fails a check and ask for a replacement before you hand over your naira.
Example
Example only: you are buying $1,000 in ten $100 notes. Two fail the watermark test. Rejecting them means you pay for $800 and the seller can replace the other two. Accepting them means 20% of what you paid is worthless, and you will have no way to get that value back from a street seller once they leave. Agree before money changes hands that any note failing a check will be replaced on the spot.
Where you buy matters as much as the check
Most fake-dollar losses happen in rushed street deals, often with a seller who offers a better rate than everyone else. Buying from licensed channels reduces the risk; see how to buy dollars legally in Nigeria. For naira notes, read fake naira notes and their security features. If you hold dollars in a bank, cash withdrawal rules are covered in withdrawing dollar cash from a domiciliary account.
Where Pryme fits
If you do not need physical cash, holding dollars electronically avoids counterfeit risk altogether. A Pryme account holds NGN, USD, GBP and EUR, each with local account details, and money stays in the currency it arrived in; see multicurrency.
Questions people ask
How can I tell if a $100 bill is fake?
Tilt it to see the blue ribbon's bells change to 100s and the inkwell bell turn green, check the Franklin watermark and security thread against the light, and feel for raised print.
Does the counterfeit pen work on dollars?
Not reliably. A bleached genuine note reprinted as $100 can pass the pen test. Use the watermark, thread and colour-shifting features instead.
What colour does the $100 security thread glow?
Pink, under ultraviolet light, according to uscurrency.gov.
Are old $100 notes still real?
Older designs exist. Compare an older note with the matching design on uscurrency.gov rather than with the 2013 features.
Sources
- uscurrency.gov: $100 note security features · accessed Oct 2026
- Saipan Tribune: Secret Service, don't rely on just one tool to detect fake bills (5 Jun 2012) · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.