Rich Zen Cerulean

Old French riche, wealthy, abundant — applied to color since the medieval period for hues that read as plentiful in pigment. Rich red, rich brown: the implication is depth combined with saturation, a color that gives the eye more to absorb. Sits at the saturated mid-light corner of the engine's grid, slightly warmer than bold and deeper than vivid.

Japanese 禅, Zen Buddhism. As a color modifier, zen implies a stripped-down-and-meditative-Mahayana quality, the visual register of Japanese-Sōtō-and-Rinzai-Zen Zen-Buddhist hand-laid rock-garden-and-tatami-and-shōji-screen meditation-hall surfaces under Sōtō-and-Rinzai-Zen Kyoto-temple-garden meditative quiet light. Sits at the modifier-and-cultural end of the grid, parallel to tao and sufi in usage.

From the Latin caeruleum, originally referring to dark blue paint pigment of the Roman world, then via French céruléen into English. As a modern art-supply name, cerulean blue is the cobalt-tin oxide pigment introduced in 1805. The color refers to a clean, slightly green-shifted blue with the matte finish of mineral pigment in linseed oil: lighter than cobalt, deeper than aqua, with the painter's weight of a word for sky.