Smoke blue is less a solid pigment than an atmosphere: the colour of a far ridge, a worn photograph, or evening gathering over rooftops. It can lend a poem emotional restraint, allowing grief or longing to appear indirectly rather than as declaration. The term suits scenes of departure, industrial landscapes, and recollections whose outlines remain visible even as their details dissolve.

Smoke blue is a softened blue-gray that suggests distance, haze, weather, or partially obscured vision. It can create emotional effects of uncertainty, calm, isolation, remembrance, or suspended time. The term is useful for skies, mountains, glass, fabric, or water when sharp outlines have dissolved. Related colors include slate blue, steel blue, dusty blue, mist gray, and blue-gray; it contrasts well with rust, copper, or pale gold.