The first luminous readers are the type of marked cards that were likely inspired by some optical gadget that came as a free gift in a box of Cracker Jacks®. The most basic luminous system is the red-lens luminous system that requires the operator to wear special red-tinted glasses. This cheating method will probably pass at the beach, or at a drunken frat party, but probably not in any other situation (not to even mention high-stake games).

The principle is very simple. The basic red-lens luminous system is supposed to work only with red-backed playing cards. The cards are to be marked with very faint green luminous ink (or daub). The red lenses act as optical filters so that the green marks become visible. In effect, when viewed through a red filter the backs of the cards will appear to be blank due to the fact that red cancels out the red design. The entire card will in fact look pink and at the same time the faint green areas will be enhanced because green is at the opposite side to red in the color wheel.

I try to update this chapter as much as I can, but if you want to keep more up to date on the latest developments in luminous readers, I recommend that you follow my blog post tagged luminous readers.


Some people have developed red contact lenses, that can be used instead of glasses. I have even heard of an idea that uses red-tinted eye drops that one is supposed to use with clear contact lenses. I have only heard of it, but never actually seen it. I've received quite a few emails from people asking me if I have any information about red contacts or red eye-drop fluid. Since I am not a doctor I can not really give any advice in that department. However, I do advice anyone who wants to experiment with such fluids to do all the testing with one eye only. The problem with such fluids is the same as with recreational drugs: they weren't made by scientists under laboratory conditions, but rather by someone in a kitchen, and without any real knowledge. Good luck.

Anyone who ever tried to make luminous readers has probably encountered some common problems: either the marks were too faint and could not bee seen even through a red filter, or the marks were too strong and could be seen even without a red filter. The problem is not that the system doesn't work, the problem is that one can not use just any red filter, and also not just any green ink. Most people will buy a cheap pair of red-tinted sunglasses and dilute some green ink from a BIC® ball-point pen in some alcohol. If you are thinking of doing that I can save you some time by advising you to skip that experiment - it won't work. I know... I tried...

glasses with red lenses for luminous readersIn order for this system to work properly one must use a very specific red filter, and a very specific green ink. The specifications are expressed in nanometers [nm] (the unit for wavelength of light) but unfortunately I am not at liberty to divulge the information.

The glasses shown on the picture cost me a considerable amount of money to make (not even counting the 5 bucks I spent for the cheap frames). The lenses were cut from special optical filters that were made to a specific tolerance for industrial applications. The filters I used to make up a pair of glasses are very strong (which is what makes it possible to see very faint marks). Looking through those filters doesn't only amplify luminous marks, but also drastically changes the world around you. I once tried to drive with those glasses on and I quickly realized I was making a big mistake and endangering everyone around me. The outside world looked like another planet, the traffic "STOP" signs were invisible and I also couldn't see any green traffic lights. That's how strong those lenses are.

The second pair of glasses shown on the picture has a mirror finish over the same type of red filters. This system works quite well for hiding the fact that the glasses are red but it does require more light, due to the fact that the mirror finish basically reduces the amount of light that passes through. The mirror finish is actually an idea that I had came up on my own while experimenting with different luminous solutions.

The ink required for a luminous system is also a very specific shade of green. Like any ink, if diluted enough it will eventually become so faint that it will be undetectable when spread thin over a surface. From my own extensive experiments I've concluded that some inks can only be seen through the correct red filters and not any red glasses. In other words, the wrong ink with the right filters won't work, and the right ink with the wrong filters won't work either. Only the correct ink with the correct filters will.


I was not able to photograph the luminous cards for this page. The problem is that in order to make a picture one must introduce an additional element - either a color film, or a CCD pickup device (if a digital camera is used). Neither one of these two elements function like human eyes, so it was not possible to produce a picture with the same luminous technology. I also felt that faking a picture would not seem right, so the only thing I can offer is a verbal description of the marks.

Good luminous marks look like faint shadows on the backs of the cards. They do not stand out like neon signs (as some may want you to believe), they may be very faint (depending on how strong the ink is), and if so, one must know what to look for. The red filters have two roles, one is to cancel out the red back design of the card, and the other role is to darken up the special ink. The marks can either be dots and lines, or simply numbers or letters with suit symbols. It should also be noted that the faces of all the red-suited cards will appear almost blank when seen through the glasses (which is why red contact lenses may not be such a good idea; if you use glasses, at least you can glimpse over the frames).


In an effort to further camouflage the scam, some people have experimented with the use of red filters hidden behind dark sunglasses (this will not work with all sunglasses). Some of those filters are advertised as soft gels that will adhere to the back of any sunglasses. Other systems use red contact lenses and the sunglasses are only used to camouflage the fact that the player has red eyes. As long as the sunglasses do not look out of place the scam would probably pass. But the question is, how practical would any of these gaffs be?

In many poker games, including the popular World Series Of Poker [WSOP], some players are known to wear dark shades (to hide their eyes, and tells). So, thanks to the abundance of televised poker games, sunglasses are nowadays commonly accepted poker accessories. Incidentally, speaking of the WSOP (and unrelated to luminous readers), have a look at the video of the 2003 WSOP Main Event and let see what you think. I bring this up because the 2003 WSOP was one of the main events that inspired millions of sucker around the world, giving the false impression that anyone can win the WSOP. If you ask me, the whole thing is a big joke. In my humble opinion, Mr. Moneymaker's poor acting and flamboyant display of fake emotions is more in line with the scripted actions of a professional wrestler at the World Wrestling Federation, than of a poker player with real money at stake. It would be hard to convince me that the whole thing was not a fix.


Do luminous readers present a real threat? Most people think of them as toys. While they may be right, some casinos do not seem to share this opinion. In many casinos the discard holders on the card tables are made out of translucent red plastic. It would be safe to assume that this is so that the pit bosses can see the cards through the red plastic, so that any luminous marks would show up to the personnel behind the pit. Notice my careful use of the word "assume". I do not "assume" that the red discard holders are made in red to spot luminous marks, I only "assume" that the pit bosses will know what to look for. However, I know for a fact that generally speaking most pit bosses don't really know what to look for.

What makes the red-lens luminous system kind of worthless is the fact that the cheat has to be wearing red glasses. Might as well attach a red clown nose to those frames, while he's at it.



Blue Lenses

I am frequently asked if it would be possible to develop a luminous system with blue glasses for blue-backed cards. The answer is, yes and no! Or better say, no and yes! No, the system would not function like a blue version of the red luminous readers, but yes, it is possible to make a luminous system with blue lenses.

The blue luminous system would not function exactly like the red system. In other words, one could not hope to place large letters and numbers across the backs of the cards and use the blue lenses to cancel-out blue back designs, like red backs are cancelled-out with red glasses so that all that's left to see would be the luminous marks. In theory, to accomplish that, one would need such dark blue lenses that the whole image would become too dark under normal lighting conditions. In effect, one could hardly see anything through such dark blue lenses without lighting up the card table like a Hollywood film set. Hardly a common practice when the boys get together to play cards.

However, a blue system can be made to work and it is hardly a new invention. I was able to find the first mention of a blue system dating back to 1909, but for some reason it is less known than the red system and almost not talked about. First of all, a blue-lens system may work best with white-border cards. The luminous marks can be painted right on the white edges of the cards either as lines, dots, shaded corners, etc. In theory one could paint over the entire width of the white borders, but a more subtle code would just use thin lines right on the extreme edges of the cards, or on the edges of the printed areas. The rest is self explanatory. Once again, to get desired results one must use a specific blue and a specific luminous ink and even then one should not expect the work to light up like "neon signs". In fact, the work will look much fainter than the marks for the red system.

luminous readers: card marking code

The system with blue lenses does not actually require the use of blue-backed cards. Once again, the function of the blue filters is not to cancel out the blue-colored back design in order to to reveal hidden marks. In this case the blue lenses are only used to enhance the luminous ink over the white areas. In fact, someone with a sharp eye could use red Bee cards and paint the luminous marks inside some of the white diamonds, instead of painting the borders of white-border cards. If you saw a guy with blue glasses while red cards were in use, would you ever suspect luminous readers?

The marking code described above for the blue system would also work with a red-lens system and blue cards. That may be a better option altogether because the marks would be more subtle and people would be less likely to suspect luminous marks if blue cards were in use. In this case the red glasses would no longer serve as filters to cancel out the red backs, but rather just to enhance the luminous marks; also the ink could be put-on much lighter because the luminous marks would not be overshadowed by a back design. Would a luminous system then work with other colors? Possibly, yes. But any luminous system would probably always have to be limited to over saturated vibrant primary colors.



Black Predators™

Black Predator Luminous ReadersThe most advanced luminous system to date consists of a pair of lenses that appear black to the casual observer. This system is sold under the brand name Black Predators™, which is a name I had come up with myself.

The ink is different from the ink used in the conventional red-lens system, and the technology that makes this system work is also different. Even the most advanced conventional red-lens system works on the principle of color blocking. This is not the case with this system.

If you try wearing the Black Predators™ on a sunny day you will discover that some colors look totally different, and some of the colors even fluoresce, when viewed through the lenses, almost as if they were illuminated with a black light at a nightclub. This phenomenon is the exact principle behind the technology that makes this system work. The lenses are capable of shifting the wavelength of light, and when the wavelength shifts, the amplitude of the waves also changes, to compensate for the shift. This is why some of the colors fluoresce under certain illuminations.

In a nutshell, the ink produces marks that are invisible to the human eye. Under proper illumination this ink can be seen through these glasses. The lenses in fact shift the wavelength of the light reflected from the ink marks to fall within the visible range that humans can see.

It should also be noted that this system cannot produce marks that are as strong as the marks produced by the best red-lens system. Although some may see this as a flaw, it is actually a desirable feature. Should anyone grab these glasses and look at the cards, chances are, they would not be able to notice the marks (at least not immediately). This should be considered a security feature, rather than a flaw.

It should also be noted that there is a percentage of people that are unable to use this luminous system. The reason is simply because some people actually suffer from some forms of color blindness. The percentage of people that suffer from one or another form of color blindness is actually higher than most people are aware of. According to various statistics, color blindness is affecting 12% to 20% of male population, and also a tiny fraction of female population. Most people don't even realize that they suffer from some form of color blindness until they take a color vision test.



Luminous Contact Lenses

Several luminous systems have been developed that use contact lenses, instead of glasses. Below are pictures of three such systems, from left to right: an old red-lens luminous system, an old blue-lens luminous system, and a modern luminous contact lens system that uses the same technology as the Black Predators™, described above.
Red Luminous Contact Lenses Blue Luminous Contact Lenses Black Predator Luminous Contact Lenses

The first image shows an old red-lens luminous system. These are the actual contact lenses that you will find advertised in some of the old Blue Books (the old crooked gambling supply catalogs). These are hard lenses and are really uncomfortable for the eyes - perhaps even risky to wear, if you value your eyes. These contacts are somewhat smaller than the average size of a human iris, and also slightly larger than the average size of a fully open pupil. The practicality of those contact lenses is highly questionable because if you put these in your eyes they will be anything but discrete.

The second image shows an old blue-lens system. These are also hard lenses and also don't stand a chance of going by unnoticed. The effectiveness of this blue system is highly questionable since this shade of blue looks nothing like the blue that is required for the blue-lens systems that I am familiar with.

Black Predator Luminous Contact LensFinally, the third image shows the only kind of luminous contact lenses that I am aware of would have any practical value. The pair of contacts on this image is my personal pair. These were made especially for my eyes, after I obtained proper eye measurements from an eye doctor. As you can see from the close-up image on the right, these contacts are mostly clear, with the exception of a dark dot in the center. This dark dot is the luminous filter that is made large enough to cover the entire open pupil. The rest of the lens is just blank, so that it doesn't affect the appearance of the iris.

If contact lenses are not made precisely for the individual that is supposed to wear them, it may actually be dangerous to put them in your eyes. First of all, the contacts must have the proper base curve - that is the inside curvature of the actual contact lens. If the base curve is too large, the lenses may float or even fall out of your eyes. If the base curve is too small, the lenses are steep, and they may prevent proper tear exchange, resulting in eye damage.

There are other potential problems. Improper use of contact lenses may result in fungal infections in your eyes and yes, a bad infection may lead to blindness. The reason why luminous contact would be at a higher risk than regular contact lenses is because they are very expensive so people are more likely to continue using them well beyond their expiration date. An old contact lens will have microscopic cracks that cannot be seen without magnification, and those tiny cracks can be home to fungus and bacteria.

Luminous contacts present some technical problems, too.

Unlike the glasses, contact lenses are glued to your eyes. This means that you cannot take them off and on, as simply as you could do with sunglasses. So, if the room is too dark, you may have trouble seeing certain cards. Depending what particular shade of red may be used to print the red-suited cards, you may be having trouble identifying red-suited cards without taking them over under a lamp. If the red-suited cards are printed with really vibrant and light red ink, you may be seeing all the red-suited cards as blanks, if the lighting is not right. So, if the flop comes 7-10-3, you may be seeing three pink cards with blank faces. But if you were just wearing luminous glasses, you could just take a quick peek from under the frames.

One other technical problem lies in the fact that every eye reacts differently to lighting conditions, and that lighting conditions are not something that you can control. So, if a room is too dark, those particular contacts may be too dark. When the eye receives less light the pupil opens up. And when you put a dark luminous contact lens over your eye, the amount of light that reaches the eye gets cut down even more, resulting in the pupil opening up even more. So, when these contact are made specifically for your eyes, the size of the filter will be made to match the measurement of your pupil in dim lighting; actually it will be made a bit larger. But if you wear them in a much darker room the pupil behind the contact lens will open up even more. Once it opens up beyond the diameter of the luminous filter, some light will suddenly poor into your eye around the filter (like a solar eclipse) and this will cause your pupil to close. But as soon as it closes, the eye realizes that it doesn't have enough light, and it will open up again. This infinite loop will actually be visible to you, as you are looking through the contacts. This is what had originally happened to me, when I had my first pair of contacts made, so I had to have them remade with a larger diameter. However, the diameter of the luminous filter should not be too large because it will cover up too much of the iris. Some people's irises open up a lot more than average - those people cannot use these contacts.

Another technical issue with contact lenses is the fact that they do not last forever. This is a fact that is very likely to be ignored by anyone paying up the required sum to have a pair of these contacts made. But, as explained above, it may be actually dangerous to wear contact lenses beyond the recommended expiration date.

There are some other technical issues with contact lenses, but they are beyond what I plan to explain in this article. Finally, the question is, how noticeable are these contacts?

I was only able to judge for myself when looking at a mirror, while only wearing one contact lens. Even then it was hard to judge because the image projected in my brain is composed of two separate images seen through two separate eyes - and one eye is wearing a dark contact lens while the other eye sees a natural image. And of course if I closed my eye with the contact lens, I would see a natural image through one eye, but I would not be able to look at the other eye, with my free eye, because the other eye would be closed. So, I had decided that the only true test would be to wear these contacts in public, while socializing with people that knew me well enough to notice a difference. When you socialize, people have a natural tendency to look at you in the eyes, so if my eyes looked weird they would certainly notice.

To cut a long story short, I performed this test with several close friends and none of them ever noticed anything. Even after I asked them if they could see anything wrong with my eyes (after enough time had elapsed) they did not know what i was talking about.

So, this test satisfied me. If my close friends were unable to notice these contact lenses, it is safe to assume that these contacts would go unnoticed in any poker game. A poker player could wear these contacts to any poker game and the suckers would have almost no chance to spot the gaff.



Hybrid Luminous Systems

The most advanced luminous system to date is the hybrid system that uses a combination of contact lenses that must be worn along with appropriate glasses. From a practical point of view a hybrid system offers several advantages.

First of all, the hybrid glasses alone cannot be used to read the luminous marks, unless they are used along with the hybrid contacts. In practical terms this means that if anyone grabs your hybrid glasses in the middle of a game and puts them on, they would not have any chance of seeing any work on the cards, unless they were wearing the same contacts you were wearing.

The second advantage is the fact that the hybrid glasses (speaking strictly of the Black Predator™ brand) have gradated lenses. This means that you can adjust for the lighting situation simply by tilting your head. The lenses are darker at the top and lighter at the bottom, so if the lighting is a bit darker you just light your head and look more through the bottom part of the glasses, but if the room has sufficient light, you lower your head and look through the top part (which offers more contrast).

Another advantage is that you would not be wearing contact lenses that are as dark as the plain luminous system. This means that you would be less likely to encounter a situation where your eyes have trouble adjusting to the darkness, and you would also not be walking around in the dark. Because remember, plain luminous contact lenses are the equivalent of wearing dark sunglasses. So, if you ever tried wearing dark sunglasses in a dimly lighted room you would understand what the trouble is.

technically speaking, the Black Predator™ luminous filters are made of several coats of different filters. A hybrid system just has some of the coats on the contacts and some of the coats on the glasses. So, when you put them both together you are looking through all the necessary filter coatings.



Other Luminous Systems

There is a luminous system described by Richard Marcus, in his book Dirty Poker. He doesn't call it "luminous" but I have decided to include it under this chapter because I feel this is where it belongs.

According to his descriptions that system uses contact lenses and a type of ink that will fade after about 20 minutes. This is a desirable feature because the evidence is gone from the cards by the time anyone decides to investigate. Considering the current advances in forensic technology it is, however, questionable if the evidence is really gone, even if the ink fades away. Nowadays they can find traces of just about anything so it may not be safe to assume that the evidence completely goes away.

Regardless, we just want to know if such system really exists.

It is hard to say exactly what system is described in that book, because the author does not share all the information. However, I can say that there is in fact a system that I know of, that uses such fading ink. But fortunately, if this is in fact the same system I am thinking of, Richard Marcus omitted two important clues about the ink that would basically give away the secret. There is one technical reason why the ink fades and he doesn't even mention anything that would give away a big clue. But, again, assuming that the system described in that book is in fact the same system I am familiar with.

Unfortunately, there is not much else I can say about that system without giving away too many clues, except perhaps that the time frame is very short, which may prove to be of limited value to go through all the trouble of juicing-up the cards during a live game.



Clear Lens System

A logical improvement on the luminous readers technology would be a system that uses clear glasses. Such system has already been developed but one would really have to have some serious connections to get a hold of the technology. For obvious reasons, this system is incomparably better than using any kind of tinted lenses; it works on a totally different principle from luminous readers and the marks appear totally different from the marks produced by luminous systems. Since this system is not presently commercially available anywhere, I am not a liberty to divulge the technology or give any hints. All that is important is to say that the system does exist.


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