What You'll Need
- A $100 Bill
- The note you want to verify for authenticity.
- Good Lighting
- Sufficient light to examine the note's security features.
- Ultraviolet (UV) Light
- To check the security thread that glows pink under UV illumination [1].
- Tilt or Angle
- To observe the color-shifting ink and 3-D Security Ribbon effects.
Step-by-Step Guide to Verifying a $100 Bill
Step 1: Examine the 3-D Security Ribbon
Locate the blue ribbon woven into the paper on the front of the note, running vertically to the right of Benjamin Franklin's portrait. Tilt the note back and forth slowly—you should see images of bells and the numeral 100 shift and move from side to side or up and down2. The ribbon is embedded in the paper, not printed on the surface, so you cannot feel it raised above the note. If the images do not move or the ribbon appears printed rather than woven, the note may be counterfeit.
Step 2: Check the Color-Shifting Bell in the Inkwell
Find the copper-coloured inkwell on the front of the note, just to the right of Benjamin Franklin's portrait. Tilt the note at different angles and watch the bell inside the inkwell—it should shift from copper to green as you change the viewing angle3. This colour change is immediate and distinct. If the bell remains a single colour or the transition is unclear, the note is likely fake.
Step 3: Verify the Color-Shifting Numeral 100
Look at the large numeral 100 in the lower right corner on the front of the note. Tilt the note and observe the colour shift from copper to green, similar to the bell in the inkwell3. The colour change should be smooth and consistent across the entire numeral. If the 100 does not change colour or appears flat and static, this is a warning sign of a counterfeit.
Step 4: Hold the Note to Light and Check the Watermark
Hold the $100 note up to a light source so that light passes through the paper. You should see a faint image of Benjamin Franklin's portrait visible from both the front and back sides of the note1. The watermark is embedded in the paper during manufacturing and matches the printed portrait. If you cannot see the watermark or it appears printed on the surface rather than within the paper fibres, the note is not genuine.
Step 5: Inspect the Security Thread Under UV Light
While holding the note to light, locate the thin vertical security thread embedded in the paper to the left of Franklin's portrait. The thread is imprinted with the letters USA and the numeral 100 in an alternating pattern1. Place the note under an ultraviolet (UV) light—the thread should glow pink1. If the thread is absent, does not display the correct text, or does not glow pink under UV light, the note is counterfeit.
Step 6: Confirm All Security Features Are Present
Review all the security features you have checked: the 3-D Security Ribbon with moving images, the colour-shifting bell and numeral 100, the Benjamin Franklin watermark visible in light, and the security thread that glows pink under UV light4. A genuine $100 note will display all of these features clearly and consistently. If any single feature is missing, unclear, or behaves differently than described, do not accept the note and report it to local authorities or the U.S. Secret Service.
Key Security Features of Genuine $100 Bills
The $100 note incorporates several distinct security features that work together to confirm authenticity: a security thread, a watermark of Benjamin Franklin, a 3-D Security Ribbon, and color-shifting ink4. Each feature occupies a specific location on the note and serves a different verification purpose, which means you can cross-check multiple elements to build confidence in your assessment. Understanding where each feature sits and what it looks like in genuine currency helps you spot inconsistencies that signal a counterfeit.
The 3-D Security Ribbon is woven directly into the paper—not printed on the surface—and runs vertically through the note2. When you tilt the bill, images of bells and the numeral 100 move from side to side or up and down within the ribbon2. This motion effect is difficult for counterfeiters to replicate, because it requires specialised manufacturing rather than simple printing. The ribbon is visible on both sides of the note and should appear as part of the paper structure, not as a separate layer or sticker.
The Bell in the Inkwell sits on the front of the note, to the right of Benjamin Franklin's portrait, inside a copper-colored inkwell. When you tilt the note, the bell shifts from copper to green3. This color-shifting ink uses optical interference technology that changes appearance depending on the viewing angle, and counterfeit notes typically fail to reproduce this effect accurately. The color shift should be smooth and consistent every time you tilt the bill.
The security thread is embedded in the paper to the left of Franklin's portrait and is imprinted with the letters USA and the numeral 100 in an alternating pattern1. Under ultraviolet light, this thread glows pink1. The thread is visible when you hold the note up to light, appearing as a thin vertical line running from top to bottom. Counterfeiters sometimes print a line onto the paper or insert a thread that glows a different color, so checking both the visible text and the UV response confirms two independent security layers.
The watermark of Benjamin Franklin appears in the blank space to the right of the printed portrait when you hold the note up to light1. This watermark is visible from both sides of the note because it is formed by varying the density of paper fibres during manufacturing1. Printed imitations often show only on one side or display visible ink dots under magnification.
The color-shifting numeral 100 in the lower right corner of the front shifts from copper to green when you tilt the note3. This feature uses the same ink formulation as the bell in the inkwell, so both elements should shift color in unison3. If one shifts and the other does not, or if the colors do not match, the note is counterfeit.
Why do these features matter in combination? Each element addresses a different counterfeiting technique: the 3-D ribbon defeats flat printing, the watermark defeats surface imitation, the UV thread defeats simple replication, and the color-shifting ink defeats static reproduction. Verifying all features together provides layered confirmation that the note is genuine. For a broader overview of how these security elements fit into US currency design, see Understanding Fake Dollar Bills: Key Features.
How to Check the 3-D Security Ribbon
The 3-D Security Ribbon is woven into the paper of the $100 note, not printed onto the surface, which means it forms part of the paper structure itself2. This distinction matters because printed ribbons sit on top of the paper and can be rubbed off or show visible ink edges under magnification, while a woven ribbon remains embedded and visible from both sides of the note. When you tilt the bill, images of bells and the numeral 100 within the ribbon move side to side or up and down2. This dynamic motion effect is one of the most difficult security features for counterfeiters to replicate, because it requires specialised manufacturing equipment rather than simple printing techniques.
To examine the ribbon, hold the note at eye level and tilt it slowly from side to side or up and down. You should see the bells and 100s shift position within the vertical blue ribbon that runs through the front of the note. The movement should be smooth and continuous, with the images appearing to slide along the ribbon as you change the viewing angle2. Genuine ribbons display a three-dimensional effect, where the bells and numerals seem to move independently of the background, creating a sense of depth. Counterfeit ribbons often show static images that do not move, or they display a printed pattern that shifts only slightly without the fluid motion of the authentic feature.
Why does the ribbon appear woven rather than printed? The ribbon is integrated into the paper during production, so it sits within the paper fibres rather than on the surface2. You can confirm this by running your finger lightly over the ribbon area—genuine ribbons feel flush with the paper, without any raised edges or texture changes. Counterfeit ribbons printed onto the surface may feel slightly raised or show ink buildup at the edges. The ribbon should also be visible from the back of the note as a faint vertical line, because it passes through the paper structure.
If you tilt the note too quickly, the motion effect may be harder to observe, so adjust the angle slowly and under good lighting to see the full range of movement. The bells and 100s should shift position with every small change in angle, not just at extreme tilts. If the images remain static, appear blurry, or show visible printing dots under magnification, the note is counterfeit. For additional context on how the 3-D Security Ribbon fits into the broader set of US currency security features, see Understanding Fake Dollar Bills: Key Features.
How to Verify Color-Shifting Ink Features
The $100 note includes two separate color-shifting ink elements: the bell inside the copper inkwell on the front of the note, and the numeral 100 in the lower right corner3. Both features use the same optical interference ink technology, which means they should shift from copper to green in unison when you tilt the bill3. This synchronized color change provides a quick visual check, because counterfeiters rarely replicate both elements with matching accuracy. If one feature shifts color while the other remains static, or if the colors do not match at any angle, the note is counterfeit.
Why does the tilting technique matter? The color-shifting ink responds to changes in viewing angle rather than changes in lighting, so the shift from copper to green occurs regardless of whether you tilt the note under bright light or moderate indoor lighting3. However, insufficient lighting can make it harder to distinguish the copper and green tones, especially if the ambient light casts a strong color tint. To observe the shift clearly, hold the note under neutral white light—such as daylight from a window or an overhead LED lamp—and tilt it slowly by approximately 45 degrees. The color change should be smooth and immediate, with no intermediate hues or patchy transitions.
The bell in the copper inkwell sits to the right of Benjamin Franklin's portrait, inside a copper-colored inkwell illustration3. When you tilt the note, the bell itself shifts from copper to green, while the surrounding inkwell design remains copper3. This selective color change within a single printed area is a key indicator of authenticity, because counterfeit notes often print the entire inkwell in a single static color or use ink that shifts to an incorrect hue. The numeral 100 in the lower right corner undergoes the same copper-to-green shift when tilted3, and both elements should change color at the same angle. If you tilt the note and observe that the bell shifts but the numeral does not, or vice versa, the note is counterfeit.
What if the color shift appears faint or inconsistent? Genuine color-shifting ink produces a clear, repeatable transition every time you tilt the note, so the effect should not fade or vary between checks3. If the color change appears weak, blurred, or shows visible printing dots under magnification, the ink is likely a printed imitation rather than genuine optical interference ink. Counterfeiters sometimes apply metallic or iridescent ink that produces a slight shimmer but does not shift cleanly between two distinct colors. Comparing the suspect note side by side with a known genuine $100 bill can help you identify subtle differences in the color-shifting behavior.
For a broader understanding of how color-shifting ink fits into the overall security design of US currency, see Understanding Fake Dollar Bills: Key Features.
How to Check the Security Thread with UV Light
The security thread in the $100 note is embedded in the paper to the left of Benjamin Franklin's portrait and is imprinted with the letters USA and the numeral 100 in an alternating pattern1. Under ultraviolet light, this thread glows pink1. This dual-layer verification—visible text in ambient light and a specific color response under UV—makes the security thread one of the most reliable authenticity checks, because counterfeiters often replicate only one aspect or use a thread that glows a different color.
Why does the UV test matter? Many counterfeit notes include a printed line or an inserted thread that appears similar to the genuine feature under normal light, but these imitations typically fail to glow pink under UV or glow a different color entirely, such as blue or yellow. The pink glow is produced by phosphorescent compounds embedded in the thread during manufacturing, and replicating this exact color response requires specialised materials that counterfeiters rarely access1. If the thread does not glow, glows the wrong color, or glows unevenly along its length, the note is counterfeit.
To perform the UV check, hold the note under a portable UV torch or place it under a UV lamp in a darkened environment. The thread should glow a consistent pink from top to bottom, with the USA and 100 text remaining visible within the glowing area1. If the thread glows only in patches or shows no response at all, the note is suspect. Comparing the suspect note side by side with a known genuine $100 bill under the same UV light can help you confirm whether the glow matches the expected pink hue.
What if you do not have access to a UV light? The security thread remains visible when you hold the note up to a light source, appearing as a thin vertical line with the alternating USA and 100 text1. This visible check confirms the thread's presence and text pattern, but it does not verify the UV response, so combining both methods provides stronger confirmation. For additional context on how the security thread fits into the broader set of US currency security features, see Understanding Fake Dollar Bills: Key Features.
How to Identify the Benjamin Franklin Watermark
The watermark of Benjamin Franklin is embedded in the paper of the $100 note and remains visible from both sides when you hold the bill up to light1. This embedded structure distinguishes genuine watermarks from printed imitations, because authentic watermarks are formed by varying the density of paper fibres during manufacturing rather than applying ink to the surface. Counterfeit notes often display a printed image that appears only on one side or shows visible ink dots under magnification, while genuine watermarks maintain consistent visibility and texture from either viewing angle.
Why does lighting matter for watermark inspection? The watermark becomes visible because light passes through areas of varying paper density, creating a translucent image of Benjamin Franklin's portrait. Insufficient lighting—such as dim indoor conditions or a light source positioned too far from the note—can make the watermark difficult to see, especially if the surrounding environment casts shadows or reflections onto the paper. To examine the watermark clearly, hold the note directly in front of a bright, diffused light source, such as a window with daylight or an overhead lamp. The portrait should appear as a faint but distinct image, with recognizable facial features and no sharp edges or printed lines.
What if the watermark appears blurred or inconsistent? Genuine watermarks display a smooth tonal gradient, where lighter and darker areas blend naturally to form Franklin's portrait1. Counterfeit watermarks printed onto the surface often show abrupt transitions between light and dark regions, or they display a pattern of dots visible under magnification. Running your finger lightly over the watermark area can help confirm authenticity—genuine watermarks feel flush with the paper, without any raised texture or ink buildup, because they are formed within the paper structure rather than applied on top.
If you hold the note up to light and see no watermark, or if the watermark appears only on one side, the note is counterfeit. The watermark should remain visible regardless of which side you view, and it should align with the printed portrait of Benjamin Franklin on the front of the note1. For additional context on how the watermark fits into the broader set of US currency security features, see Understanding Fake Dollar Bills: Key Features.
Troubleshooting Authentication Issues
When verifying a $100 bill, you may encounter some challenges or uncertainties. Here are some common issues and their solutions.
Colour-Shifting Ink Not Visible
The colour-shifting ink may not be visible if the lighting is insufficient or if the note is tilted too quickly. To correct this, ensure the note is under good lighting and tilt it slowly by roughly 45 degrees to observe the colour shift from copper to green.
Security Thread Not Glowing Under UV Light
If the security thread does not glow pink under UV light, it may be due to incorrect UV light wavelength or insufficient darkness. Ensure you are using a UV torch or device with the correct wavelength and that the environment is dark enough to observe the glow.
Watermark Not Visible
The watermark may not be visible if the lighting is not sufficient or if the note is not held up to the light correctly. To correct this, hold the note up to a bright light source, such as a window or overhead lamp, and look for the faint image of Benjamin Franklin in the blank space to the right of his printed portrait.
Differences Between Older and Newer $100 Bills
Older $100 bills may not have the same security features as newer ones. If you are unsure about the authenticity of an older bill, consult the relevant resources or contact the US Secret Service for guidance on verifying its authenticity.
Receiving a Counterfeit Bill
If you receive a counterfeit $100 bill, do not attempt to return it to the passer. Instead, contact local law enforcement or the US Secret Service to report the incident. Follow their instructions for handling and submitting the counterfeit note.
Key Takeaways
To ensure the authenticity of a US $100 bill, remember to:
- Check the colour-shifting ink by tilting the note to verify the bell in the copper inkwell and the numeral 100 change from copper to green.
- Examine the 3-D Security Ribbon for moving images of bells and 100s.
- Hold the note up to light to see the watermark of Benjamin Franklin from both sides.
- Verify the security thread is embedded in the paper and glows pink under UV light.
For a deeper understanding of US currency security features and how to identify counterfeit bills, visit our guide on Understanding Fake Dollar Bills: Key Features.