Meet 'Olo': A never-before-seen colour, revealed by scientists using lasers

In a world where the visible spectrum is considered a constant, a team of scientists in the United States is challenging the very boundaries of human perception with the bold claim of witnessing a colour never seen before—one that lies outside nature’s palette. They’ve named it “Olo.”

The discovery comes from researchers at the University of California, Berkeley, who used advanced laser technology to stimulate individual cone cells in the retina—specifically the elusive ‘M’ cones that natural light can never activate in isolation. This experimental method resulted in a visual experience so vivid and unusual that researchers say no digital display or paint swatch can replicate it.

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“It was jaw-dropping. It’s incredibly saturated,” said Ren Ng, an electrical engineer on the team.

Overwhelmed with the new discovery, many posted on X that how scientists have tricked the eye into seeing a colour nature never could.

What is 'Olo' and why can't we see it?

Human eyes perceive colour through three types of cone cells—L (long, red), M (medium, green), and S (short, blue)—each responding to different wavelengths of light. In the real world, all light sources stimulate multiple cones simultaneously, making it impossible to isolate the response of M cones alone. This is why a purely M cone-triggered colour is unseeable in daily life.

To overcome this, the Berkeley team began by mapping individual cone cells in the eye. Using a tool they’ve named Oz Vision (a nod to the Emerald City in The Wizard of Oz), they fired microscopic laser pulses into only the M cones, creating a patch of colour in the visual field about twice the size of a full moon.

They dubbed this new colour ‘Olo’—symbolising binary code 010, representing exclusive stimulation of the M cones with L and S cones turned off.

“There is no way to convey that colour in an article or on a monitor,” said Austin Roorda, a vision scientist on the team. “The colour we see [on-screen] is a version of it, but it absolutely pales by comparison with the experience of Olo.”

Though visually described as "blue-green," all five human subjects who experienced Olo insist that the term does not do it justice. It is more saturated and intense than anything within the conventional visible spectrum.

Not everyone is convinced!

Not all experts are sold on the claim. John Barbur, a vision scientist from City St George’s, University of London, remarked:

“It’s not a new colour. It’s a more saturated green that only appears when M cones are stimulated in isolation. The value of this work is limited.”

Barbur argues that the phenomenon, while interesting, doesn't constitute the discovery of a new colour but rather an artificially generated visual effect.

The bigger picture: Beyond just colour

Despite the debate, the experiment may open new doors in visual neuroscience. The team believes the Oz Vision tool could be instrumental in studying how the brain constructs colour perception and how specific cone activation affects our visual experience.

This laser-based stimulation technique might also aid research into visual disorders such as retinitis pigmentosa or colour blindness. By targeting cones in isolation, scientists may better understand dysfunctions in the visual system—and possibly design future therapies.

As for mass accessibility? That’s a long way off.

‘This is basic science,” said Ng. "We’re not going to see Olo on any smartphone displays or any TVs any time soon. And this is very, very far beyond VR headset technology."

So, for now, Olo remains a rare neurological gem—seen only by five individuals and locked behind the precision of experimental laser science.