Indigo is a plant that has a blue dye in it. Henna is never black, henna never dyes hair black, but powdered indigo resembles powdered henna and it DOES dye hair black. So, when indigo was sold as hair dye, it was called âblack hennaâ. When it was sold to dye cloth, it was called indigo. Made hygienically without the addition of any harmful chemicals, the Natural Black Henna Powder is very skin-friendly.