Olo

Olo is an imaginary color discovered in April 2025 by a team of scientists at the University of California, Berkeley, that cannot be perceived with the naked eye. "Researchers used lasers to create stimulation in individual cone cells in the retina — leading to the perception of a completely new colour." The intense blue-green color was seen by five people when "researchers used lasers and tracking technology to selectively activate certain cells in their retinas." The research was reported in April of 2025.

Discovery

To be sure that olo is really a previously unseen color, the scientists did certain tests. One test was a color-matching test. They had the five participants try to match olo to a blue-green color from a near-monochromatic laser. This kind of laser makes the most saturated colors that can be seen naturally. "Participants could only match olo to this blue-green hue by reducing its saturation, confirming that olo lies outside the boundaries of normal human color vision." The name "olo" comes from the binary 010, which represents that only the medium cones are fired but not short or long.

Closest visible color to olo.

However, one scientist says "it is not a new colour" but rather a previously unseen "more saturated green."

It is claimed that #00FFCC, the hex color for turquoise, is the closest color to olo that screens can produce.

Olo can only be seen by pointing a laser into someone's eyes. Five volunteers were able to view the color at the risk of their eyesight.