is indigo a shade of blue or purple
Indigo Indigo is a deep and rich color close to the color wheel blue (a primary color in the RGB color space), as well as to some variants of ultramarine. It is traditionally regarded as a color in the visible spectrum, as well as one of the seven colors of the rainbow: the color between purple and blue; however, sources differ as to its actual position in the electromagnetic spectrum.
Indigo Isaac Newton introduced indigo as one of the seven base colors of his work. In the mid-1660s, when Newton bought a pair of prisms at a fair near Cambridge, the East India Company had begun importing indigo dye into England,[15] supplanting the homegrown woad as source of blue dye. In a pivotal experiment in the history of optics, the young Newton shone a narrow beam of sunlight through a prism to produce a rainbow-like band of colors on the wall. In describing this optical spectrum, Newton acknowledged that the spectrum had a continuum of colors, but named seven: "The originall or primary colours are Red, yellow, Green, Blew, & a violet purple; together with Orang, Indico, & an indefinite varietie of intermediate gradations."[16] He linked the seven prismatic colors to the seven notes of a western major scale,[17] as shown in his color wheel, with orange and indigo as the semitones. Having decided upon seven colors, he asked a friend to repeatedly divide up the spectrum that was projected from the prism onto the wall:
Rainbow Rainbows span a continuous spectrum of colours. Any distinct bands perceived are an artefact of human colour vision, and no banding of any type is seen in a black-and-white photo of a rainbow, only a smooth gradation of intensity to a maximum, then fading towards the other side. For colours seen by the human eye, the most commonly cited and remembered sequence is Newton's sevenfold red, orange, yellow, green, blue, indigo and violet,[2][3] remembered by the mnemonic, Richard Of York Gave Battle In Vain (ROYGBIV).
Marcus Álvarez