Indigo is among the oldest dyes in human history — evidence of indigo-dyed textiles dates to 6,000 years ago in Peru, and to ancient Egypt, Mesopotamia, and India. For millennia, it was one of the most valuable trade commodities in the world. The discovery of synthetic indigo by Adolf von Baeyer in 1882 (for which he won the Nobel Prize in 1905) destroyed the Indian indigo industry and transformed global chemistry.

Deep, mysterious, and slightly otherworldly. Indigo sits between blue and violet — it has the depth of night sky and the mystery of twilight. Associated with intuition, the subconscious, and spiritual perception. In chakra systems, indigo corresponds to the "third eye" — the centre of intuition and inner knowing.

Indigo plantations in colonial India, the American South, and the Caribbean were sites of brutal exploitation — enslaved people and indentured workers produced the dye under terrible conditions. The Indigo Revolt in Bengal (1859–1860) was a significant uprising by indigo farmers against British planters — one of the earliest organised resistance movements against colonial exploitation. Isaac Newton included indigo as one of the seven colours of the rainbow specifically to reach the number seven (for musical, astrological, and mystical reasons) — many scientists argue the spectrum contains six perceptually distinct colours, not seven.