Indigo historically came from the plant “Indigofera tinctoria.” Its name became the root of the word “dye” in Greek, which is “indikon” and in Latin “indicum.” The reason the color indigo is so associated with the processing of dyeing fabric is the color was so popular in India and became fashionable in Europe.
A discovery occurred during the 1600’s. Glass prisms separated invisible light into colors of the rainbow. Indigo, chosen by Isaac Newton, became one of the seven colors of the visible spectrum of light.
The colors of the rainbow or the spectrum as determined by Newton were:
Besides the primary colors of red, green, and blue, the colors of the rainbow (which are the same as those shown by light passing through a prism) have great significance. In modern times, synthetic dyes make the color of indigo. Nevertheless, indigo still retains its fascination and historical significance.