What color is indigo?

Indigo is a shade of blue that ranges from a deep violet blue to a dark, grayish blue. It is named from the blue dye extracted from plants of the genus Indigofera.

Isaac Newton named indigo as one of the seven colors of the visible spectrum, which correspond to the colors of the rainbow. Indigo lies between blue and violet and is generally classified as having a wavelength between 450 and 420 nanometers, though this is subject to some dispute.

India was an ancient manufacturer and supplier of indigo dye, and the name stems from the Greek word "Indikos" which means "of India."