Newton's seven
The seven colours Isaac Newton named in the spectrum in 1704. He chose seven to match the notes of a musical scale; the spectrum itself has no divisions.
Spectral red
#FF0000Spectral orange#FF7F00Spectral yellow#FFFF00Spectral green#00FF00Spectral blue#0000FFSpectral violet#8F00FFSpectral indigo#4B0082A named colour is not a fixed standard: different sources give different values for the same name. Each swatch links to where its value comes from.