INDIGO, the brilliant blue dye made from plants, was one of the US's slavery-based cash crops

But before it was exported by the US, indigo dye had been one of the world's great treasures for thousands of years.

Referred to by some as "blue gold", it caught the imagination of connoisseurs and merchants and colonialists with its power to bewitch and its transcendent beauty - and the value and demand for indigo became ungovernable.

It sparked bitter trade wars and touched off impassioned European and North American legislation and political debate and became known as The Devil's Dye.

- delanceyplace.com