They have to do with something related to the perception of an aura. There is indeed affinity and correspondence between physical colors and auric (or aural, 'auroral') colors, in the sense that physical colors themselves have a moral and spiritual quality
Corbin establishes the aura as a mode of visionary apperception linking physical color to moral-spiritual states, providing a methodological basis for distinguishing suprasensory perception from hallucination in Sufi psychology.
, The Man of Light in Iranian Sufism, 1971thesis