The formalized seven-chakra system is basically a modern conceit, and the correspondence to the septenary colors of visible light is a fairly new innovation, introduced through "Theosophy" movements in the past century, by people like Alice Bailey.
In the available mystical literature of the Tantriks, Tibetan Buddhism, and other assorted esoteric traditions, many chakras are actually mentioned and there was little attempt to systematize them (outside an individual work or school of thought), or to implicate an obvious order to their manifestation.
The color-coded chakras of modern "esoteric" works seem quite different from the original ideas, and their common association with physiological function and correspondences to psychological development aspects would at best place them as "etheric" in nature and linked to the personality and its libido energy rather than to cosmic forces. If you have decent concentration and skill at visualization, it is relatively easy to access them.
The chakras spoken of in traditional literature are perceived in advanced states of meditation by adepts, many of whom devoted their entire lives to such contemplation and esoteric development. Patanjali among others speaks about the powers of successfully performing samadhi on some of them in his Yogasutras.
This is not to say that modern ideas about Kundalini and the chakras are necessarily wrong or useless, only that they are not ancient esoteric knowledge based in millenia of universal experience, confirmed by countless Masters, Gurus, and Sages, but in all probability are fairly modern inventions by early 20th-century occultists who popularized esotericism.
Attempts to combine the chakra system with other devices of Western esotericism have also been problematic. Dion Fortune (aka Violet Firth) and Aleister Crowley, for example, gave chakra attributions to the Sephira which are quite at variance with one another.