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.^[1] "Researchers used lasers to create stimulation in individual cone cells in the retina — leading to the perception of a completely new colour."^[2] 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."^[3] 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."^[4] The name "olo" comes from the binary 010, which represents that only the medium cones are fired but not short or long.^[5]

Closest visible color to olo.

However, one scientist says "it is not a new colour" but rather a previously unseen "more saturated green."^[6]

It is claimed that #00FFCC, the hex color for turquoise, is the closest color to olo that screens can produce.^[7]

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.