Klein's ultramarine, the deep, rich blue the artist patented as his own.
International Klein Blue is a deep blue.
It can be described as deep, rich, dark and dim.
Set in white, because white reads best on it.
International Klein Blue (IKB) is a deep blue hue first mixed by the French artist Yves Klein. IKB's visual impact comes from its heavy reliance on ultramarine, as well as Klein's often thick and textured application of paint to canvas.
Read on WikipediaBlue is one of the three primary colours in the RGB (additive) colour model, as well as in the RYB colour model. It lies between violet and cyan on the spectrum of visible light. The term blue generally describes colours perceived by humans observing light with a dominant wavelength between approximately 450 and 495 nanometres. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.
Read on WikipediaProper noun