How Do Counterfeit Detectors Work? 5 Technologies Behind it

Since the invention of currency, several criminal minds have given birth to different ideas to counterfeit money and pass them as authentic cash. Coming down from thousands of years, the business of counterfeiting money is rampant in today’s world.

And what’s more, modern technologies have helped these criminals become more proficient in producing counterfeit money, which is more difficult to detect than ever!

but How Do Counterfeit Detectors Work? Is it reliable?

However, the same technologies can also create far more sophisticated counterfeit detectors with reshaped security features that made counterfeit identification easier and made it harder for criminals to create duplicate notes.  

Counterfeit detectors are nothing but machines with a huge responsibility to detect a banknote’s security features and determine whether they are genuine or fake. A counterfeit detector employs different detection methods and several technologies to verify the authenticity of the banknote under their surveillance.

The more technical methods a detector uses, the more efficient it is in determining the validity of a banknote by verifying all its security features.

If you own a business that leaves you at risk of counterfeit fraud and wants to know if a counterfeit detector can sniff out forged cash, then this article is for you. Continue reading to know how banknotes are designed to prevent counterfeiting and how do counterfeit detectors work to detect money forgery.

How are Banknotes Designed to Prevent Counterfeiting?

Before we go into the depth of how counterfeit detectors work, first, let us focus on how exactly are banknotes designed in the first place for the detectors to determine their authenticity.

While minting money bills, the banks use a range of specific security features for the counterfeit detectors to look for to identify those unique features before declaring the banknote as genuine. These special features include treasury papers, watermarks, security threads, magnetic inks, microprinting, and many unique features such as colors, images, size, weight, UV rays properties, and holographic features.

How Do Counterfeit Detectors Work

Treasury Paper

The original currency uses special treasury papers to mint the banknotes. They either employ polymers or a cotton-linen blend with 25% linen and 75% cotton. Some notes even have tiny red and blue fibres embedded in them.


Some banknotes use special watermarks which will only be visible when exposed to light.

Security threads

Money bills also use security thread embedded vertically and is at a different position for different denominations. The security threads are unique to the banks, and hence a detector can easily identify them as genuine.

Magnetic and Infrared Inks

Some notes use magnetic inks to proclaim their authenticity to the detectors that can sense the magnetic properties of inks and identify the genuine ones. Certain banknotes also use infrared inks that either reflect or absorb infrared light when subjected to the ray.


Some banks employ microprinting to design their notes in a way that would make them easily identifiable. They use tiny letters that appear as a simple line to the naked eyes, but a counterfeit detector can easily read them and determine their authenticity.

UV Properties

The security threads of the money bills are designed to shine under ultraviolet light. So, when a note passes through the UV rays, they glow, each denomination emitting a different light.

A counterfeit detector looks for all these features in the banknote under its surveillance to determine its authenticity. Let us now see how it’s done.

How do Counterfeit Detectors Work?

A counterfeit detector works at various levels putting several technologies to scrutinize a banknote and judge the authenticity.

Let us now swipe through the methods one by one.

UV Counterfeit Detection

This is the most common method used by counterfeit detectors. The device just has to shine ultraviolet light onto the bills and check if the security thread of the notes is emitting a glow to proclaim their authenticity. Some notes have UV marks created using non-visible dyes, which glows when subjected to UV rays.

Magnetic Counterfeit Detection

Another primary method that a counterfeit detector uses is magnetic verification. The device is equipped with magnetic sensors to identify the magnetic ink with which the elements on the note are printed and the metallic threads placed on some strategic regions of the authentic banknotes. 

Infrared Counterfeit Detection

Certain banknotes armed with infrared inks pass through the inspecting eyes of the counterfeit detectors equipped with infrared rays. These detectors employ a range of infrared reflecting and infrared absorbing sensors to check how the banknotes respond under infrared frequencies before declaring a note as a genuine one. 

Watermark Counterfeit Detection

Counterfeit detectors also use a special light to view the watermarks, invisible to the naked eyes. The watermarks are unique and can only be built into authentic banknotes. So, that makes it easier for a detector to identify the genuine one.

Size, Weight, Colour and Image Counterfeit Detection

Some counterfeit detectors are even designed to inspect a note based on its size, weight, color, and image. 

Many banks produce notes which vary in size and weight based on the denominations. This is done to combat bleaching, i.e., printing a counterfeit note with a higher value than a lower one. Counterfeit detectors are trained to catch these kinds of size and weight discrepancies as well.

Some counterfeit detectors employ color spectrum analysis to verify whether the colors, patterns, and images used in the banknotes follow the color code, which is unique to each denomination.

Every banknote has complex patterns printed on its surface using specialist colored inks. Counterfeit detectors use a susceptible spectrum sensor to scan a banknote and then compare it with the correct image preserved securely in its memory to verify its authenticity before declaring it as a genuine note.

Counterfeit detectors come in different sizes, forms, and prices that determine their proficiency and effectiveness. But whatever be their specifications, their intention is the same—to scrutinize banknotes and detect counterfeit money.

So, suppose you can introduce any of these counterfeit detectors into your business environment. In that case, you will be able to save yourself, your employees, and your company from the threats of counterfeit fraud.


considering the rise of criminal masterminds and their access to modern technologies, it is not sufficient to rely only on one or two verification methods. So, while putting your choice on a counterfeit detector for your company, make sure that you check for more than one factor. Review all your options and invest in the one that promises to provide multiple testing methods to authenticate a banknote. 

Technological improvements have made it hard to detect counterfeit money, and hence counterfeit detectors are required to work even harder to raise the bar high and combat money forgery.

Jaren worked for nearly 10 years in the industry. He started his career with FedEx but he later also worked with companies like USPS and Deutsche Post.

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