Some of the "blues" generated in nature rely on specific physical structure or other tricks to appear blue. This means they reflect predominantly blue light, b

Some of the "blues" generated in nature rely on specific physical structure or other tricks to appear blue. This means they reflect predominantly blue light, but may not retain that "blueness" when ground/processed into a pigment. That's one reason there are few natural organic blue pigments, even the ancient Egyptians relied on chemical solutions for "Egyptian Blue". https://en.wikipedia.org/wiki/Blue#Pigments_and_dyes https://en.wikipedia.org/wiki/Blue#Pigments_and_dyes Interestingly, the one dye listed in the link above that came from a plant is indigo, which is extracted from the green leaves of the plant https://en.wikipedia.org/wiki/Indigofera_tinctoria https://en.wikipedia.org/wiki/Indigofera_tinctoria . There's no animal or plant I know of that both appears blue and could be used to create even a poor blue pigment, though I'd definitely be interested in any exceptions I haven't heard of. https://www.youtube.com/watch?v=3g246c6Bv58 https://www.youtube.com/watch?v=3g246c6Bv58