Owning an oil painting made with expensive blues was once a status symbol. Painters who were poor or didn’t live in cosmopolitan areas never used any blue at all. Jan van Eyck used lapis – but only at the request of his patrons.
Blue is the most commonly confused color in terms of its hue temperature. There is a widely held misconception that all blues are cool. This is not at all the case: Indanthrone, Cobalt, and Phthalo Blue, for example, are warm, and Ultramarine Blue is so warm that it’s almost purple.