Tyrian Purple

"It took tens of thousands of desiccated hypobranchial glands, wrenched from the calcified coils of spiny murex sea snails before being dried and boiled, to colour even a single small swatch of fabric, whose fibres, long after staining, retained the stench of the invertebrate's marine excretions. Unlike other textile colours, whose lustre faded rapidly, Tyrian purple ... only intensified with weathering and wear – a miraculous quality that commanded an exorbitant price, exceeding the pigment's weight in precious metals." ~ BBC

So it's a purple dye that smells of where it came from and gets richer over time with use. Perfect.