Why Did Chakras Acquire the Colors of the Rainbow?

Red at the bottom, followed by orange, yellow, green, blue, indigo, and violet.
Today, this sequence seems so familiar that it is easy to assume it comes directly from ancient Indian tradition.
But classical Tantric texts did not describe the chakras as seven rainbow colors arranged in the modern sequence.
What Colors Were Used Historically?
Colors did appear in older chakra systems, but they varied depending on the specific text and tradition.
One chakra might be described as red, another as white, smoky, or radiant. Color could be associated with a lotus, deity, element, or a particular visualization practice.
In other words, there was no universal rule stating:
the first chakra is red, the second is orange, the third is yellow…
Such a standardized system did not exist.
Where Did the Rainbow Come From?
Twentieth-century Western esotericism played a major role.
In 1927, the Theosophist C. W. Leadbeater published The Chakras, which included colored illustrations of the energy centers. His system already differed significantly from earlier Indian descriptions.
The familiar modern model, in which the seven chakras correspond sequentially to the colors of the visible spectrum, became firmly established much later — especially in New Age literature of the 1970s. Researchers studying the history of the Western chakra system have noted that the combination of rainbow colors and specific psychological qualities assigned to each chakra became standardized during this period.
Why Did This System Become So Popular?
Because it is extremely convenient.
Seven chakras. Seven colors. A clear sequence from bottom to top.
The system is easy to illustrate, remember, and explain.
But convenience does not make something ancient.
The modern rainbow chakra system developed through the blending of Indian ideas with Western occultism, psychology, and New Age culture.
So familiar green “heart chakra” or blue “throat chakra” belongs primarily to a modern interpretive system — not to a universal map used by Tantra for thousands of years.