How come there's no all 7 colours of the actual इंद्रधनुष on a एल जी बी टी इंद्रधनुष Flag instead of only 6? I'm just curious that's all. Does anyone know for sure the right answer to this simple सवाल of mine?

What ever happened to the last colour, colour indigo? It supposed to be the colour of the last stripe on a इंद्रधनुष Flag. Where did it go & how come the 7th colour of a real इंद्रधनुष somehow has managed to get लॉस्ट since it was created back in 1978?