Heritage
Blue is one of the hardest colors for nature to make with pigment — and, historically, one of the most expensive to paint with. Ultramarine, ground from lapis lazuli mined in Afghanistan, could cost as much as gold in Renaissance Europe; Vermeer used it lavishly. Egyptian blue (the first synthetic pigment, ~3000 BCE) was lost for centuries and rediscovered in the 19th. Prussian blue (1704) quickly gave painters a cheap alternative to ultramarine; Yves Klein's IKB (1960) re-aristocratized blue.
