While indigo itself is naturally derived from a plant, growing demand for blue jeans throughout the 20th century gave rise to synthetic indigo, which is now more commonly used. But indigo ...

A piece of approximately 6,000-year-old woven cotton material from Peru gets its blue hue from indigo dye, making it the oldest known example of the colorfast dye’s use anywhere, researchers find.

This cotton band or belt from Huaca Prieta is between 4100 and 3500 years old, and has an indigo-blue center stripe accented with yellow ochre. Photograph courtesy Lauren A. Badams Researchers ...