Blue fabric dyes were rare and very expensive until aniline and its colored derivatives were synthesized. There was Tyrian purple and royal blue [1], both derived from marine mollusks.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Tyrian_purple" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Tyrian_purple</a>