Which color doesn't exist on the light spectrum?

On the spectrum of elements, all visible colors and non-visible have specific wavelengths which distinguish them from the other colors on the color wheel. Magenta, because it doesn’t exist on the light spectrum, doesn’t have one. Rather, it’s something our brain creates to fill in space in a way that makes sense.

When trying to determine color, the brain simply averages the colors to come up with an outcome. If you mix green and red light, you’ll end up with a yellow light because the brain has averaged it. When you mix red and purple light, your brain averages them. Ultimately, this would reasonably come out to green — that’s the average wavelength — but because your brain wants the outcome to make logical sense, it mixes the colors and you get magenta.

We view most colors as averages of 3 main colors. The brain only has 3 photoreceptors. Because of this, the 3 colors we can technically see are red, blue and green. Arguably, color doesn’t actually exist because it’s just an interpretation made by our brains to distinguish different wavelengths from one another.

Magenta might not exist, but there are also ways to create imaginary colors — colors that can’t exist, but which you can see temporarily by looking at a chimerical color demo template. This happens when you stare at one image for a bit, until some of the cells perceiving the color become tired. After this, you can switch to looking at another, very different color, which will let you see the imaginary colors.