Spectral color

In reality, the spectral bandwidth of most primaries means that most color spaces are entirely non-spectral.

The first person to decompose white light and name the spectral colors was Isaac Newton.

In modern divisions of the spectrum, indigo is often omitted and a blue-green color is sometimes included.

In the table below, note how wavelength is not proportional to hue (which is approximately perceptually uniform).

Color systems such as ISCC-NBS attempt to divide the spectrum into sections that appear perceptually uniform.

On the other hand, Newton's sections are approximately uniform in size as they would have physically appeared in the diffracted spectrum, i.e. each about 40nm "wide".

The hue that a given monochromatic light evokes is approximated at the right side of the table.

A rainbow is a decomposition of white light into all of the spectral colors.
Laser beams are monochromatic light, thereby exhibiting spectral colors.
CIE xy chromaticity diagram
The spectrum colors are the colors on the horseshoe-shaped curve on the outside of the diagram. All other colors are not spectral: the bottom line is the line of purples , whilst within the interior of the diagram are unsaturated colors that are various mixtures of a spectral color or a purple color with white , a grayscale color. White is in the central part of the interior of the diagram, since when all colors of light are mixed together, they produce white .