Indigo dye is used as a natural hair dye to get a range of different colors in a safe non-damaging hair dye. Using a combination of indigo and henna yields a range of colors from reddish brown to dark brown, and even black. Use alone, indigo darkens already dark hair.
100% Organic Hair Color - Without Indigo Collection – Radico USA
100% Organic Indigo Powder for Hair Dye, Black, Coloring, for Use with Pure Henna |100 Grams/| Henna Cosmetics