I'd like to add that different colors means different things in different parts of the world. In Europe and the Mediterranean, purple was a rare and expensive color typically reserved for royalty. In East Asia by contrast, purple was not a royal color probably because it was not as rare. Beginning in the Zhou Dynasty, the kingdoms of the region had learned to produce synthetic purple & synthetic blue called "Han purple" and "Han blue" through a combination of mixing and/or melting different ores together. The Qin Terra Cotta soldiers had their some parts of their armor painted with some purple and blue colors. By the time the synthetic dyes were no longer as common, the culture(s) at that point had already associated other colors with royalty.