When I commissioned the logo for the Modern Platonist, I asked the designer to use the International Klein Blue, to which I'm very attached. Of course, he did not. Oddly, still today I admire the work of Yves Klein, even though it is degenerate art.
Klein was a Rosicrucian. I was raised in a house full of Rosicrucian symbolism, because it had been built by the founder of AMORC in Spain, Carme Manrubia. One of the rooms, where rituals were performed, featured a beautiful International Klein Blue glass window.