The world is filled with millions of colors that allow us to better interact with it. This is why colorblindness is a serious disability that goes well beyond just making it hard to pick out matching clothes for the day. The eyes of humans are able to see a massive range of colors, but there are some animals that can see even more than we can (and many that can see far fewer).

The range of colors that humans can see will vary somewhat from person to person, but according to a new study published in the journal Science Advances, there are just five people in the world who have seen the color known as ‘olo.’ This is not because they happened to evolve a weird set of eyes, but because the researchers who published the study used an advanced laser technique to ‘force’ their eye to see this color that would otherwise be impossible.

The participants in the study said that olo is somewhat like turquoise, but not exactly. It is notoriously difficult to explain a color to someone who has never seen it. Imagine if you had a friend who was entirely color blind and they asked you to describe the color blue, for example. What words could you even use to allow them to understand what blue really is. It’s simply one of those things that you really have to see to understand, and when it comes to olo, humans cannot see it naturally.

Coauthor of the study, Austin Roorda is a vision scientist at UC Berkley. He recently talked to The Guardian about the experience, saying:

“There is no way to convey that color in an article or on a monitor. The whole point is that this is not the color we see, it’s just not. The color we see is a version of it, but it absolutely pales by comparison with the experience of olo.”

So, how did the researchers help these five lucky people see olo? Well, once you hear about the process, you might not want to see it for yourself.

The short explanation is that the researchers fired lasers into their eyes to force them to see the color.

The longer explanation requires an understanding that our eyes determine color based on the photoreceptor cells in our retinas called cones. Humans normally have three types of cones, each responsible for a different wavelength of light. The L cones are for long wavelengths, the M cones for medium, and the S cones for short. This means that when you are seeing red, your L cones are activated because red is a longer wavelength of light. M cones are for green, and S cones are for blue.

Just like with a TV or other monitor, the shades of colors are made by mixing different wavelengths of light in different amounts. Our eyes can activate the L and S cones on their own naturally, but for the M cones, this is not possible. Any wavelength of light that will activate the M cones will also activate either the L, The S, or both at the same time. Ren Ng is a coauthor of the study and a professor of electrical engineering and computer science at UC Berkeley. Talking about the study, he told Scientific American:

“There’s no light in the world that can activate only the M cone cells because, if they are being activated, for sure one or both other types get activated as well.”

These researchers came up with a way to do what nature could not. Activate only the M cones in the eyes of the participants. They did this by mapping their retinas to locate the precise position of their M cones. They then had the participants enter a dark lab where a tiny pulse of light was fired directly into each M cone cell, one at a time. As soon as this happened, the participants were able to see a patch of the color olo in their vision about twice the size of a full moon.

The patch of olo would start fading quickly as the M cones went back to their natural state, but the memory of the color remained.

The study is very interesting, but it isn’t just for the novelty of a new color. The authors hope that someday, this technology could be used to help those with color blindness to see colors, even if only temporarily (for now).

If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?