I am free now to be academically indulgent and just because I found a whole bunch of words today related to colo(u)r. The Phrontistery [n. a thinking place; Gr phrontisterion from phrontistes a thinker, from phroneein to think] is a veritable shrine to lexical intrepidity, claiming the International House of Logorrhea, a dictionary of obscure words, the Compendium of Lost Words, and "many other glossaries, word lists, essays". In short, loads of etymological related goodness.
One treat is a list of 168 of the most antiquated, recherché, and useful terms describing color that stretches way beyond that of your more common, pedestrian rainbows. Selected favs:
Amaranthine : a dark reddish purple color; eternal, infinite; of or related to the amaranth plant; of an imaginary flower that never fades
Eau-de-nil : a pale yellowish green color (like the Nile, presumably)
Ferruginous : rust colored; containing iron; brown approaching yellow
Gamboge : a strong yellow color; partially transparent dark mustard yellow pigment
Greige : hilariously, it's a color "between gray and beige, closely akin to the [even more blandly, accurately named] taupe"
Lurid : doesn't just mean "unnaturally or unpleasantly vivid in color" but especially when applied to red-yellow and yellow-brown mixtures (which is why an alternate meaning of lurid is "shining with an unnatural red glow as of fire seen through smoke; 'a lurid sunset'; "lurid flames'")
Umber : brownish red; obtained from natural clays variously colored by the oxides of iron and manganese
Rhodopsin : "visual purple" further defined as "a red photopigment in the retinal rods of vertebrates"
Vermeil : bright scarlet red or vermillion color; gilded silver
Viridian : chrome green; a bluish green pigment made from a foam of chromic oxide