What is another word for "indigo"?

Roget's Thesaurus (1911) lists these synonyms for "indigo": atmospheric, azure, bice, bloom, blue, blueness, bluish, cerulean, cerulescent, cobalt, cold, cyanogen, indicolite, lapis, lazuli, powder, retiring, sapphire, sky-blue, smalt, syenite, turquoise, ultramarine, watchet, zaffer.