This may be too long to read and navigate comfortably. This article is about the colour. Coronation of Louis VIII and Blanche of Castille 1223. Blue is one of the three primary colours of pigments in painting and traditional colour theory, as well as in the RGB colour model. Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments. Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and sometimes with sadness.