Smoldering Rigel Cerulean

The progressive participle of smolder, to burn slowly without flame. Used as a color word since the late nineteenth century for the deep reds and oranges of barely-flame coal — the warm saturated darks where the heat is internal rather than emitted. Sits in the bold-and-warm corner, slightly less luminous than burning and slightly less calm than rich.

Arabic rijl-al-jawzā', foot-of-Orion. As a color modifier, rigel implies a blue-supergiant-and-Orion-foot quality, the visual register of Orion-Hunter-and-winter-blue-supergiant-Rigel hand-blue-supergiant-and-Orion-foot Orion-Hunter-and-winter-blue-supergiant-and-Bortle-1 rigel-and-blue-supergiant-and-winter-zenith surfaces under Orion-Hunter-and-winter-blue-supergiant-and-Bortle-1 January-and-February-winter-Orion deep-blue-stellar-light. Sits at the modifier-and-cosmic end of the grid, parallel to vega and deneb 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.