Klein Blue sits in the vibrant band at #002fa7. The name carries a real history — klein has been describing this part of the spectrum for longer than the spectrum has been a word.
Yves Klein
Yves Klein, the French artist (1928–1962) who patented International Klein Blue (IKB) in 1960 — a synthetic ultramarine suspended in a binder that preserved the matte saturation of the raw pigment. The color refers to a Klein monochrome painting: a deeply saturated, slightly violet-shifted blue with the velvet-matte finish of un-glossed pigment. Deeper than ultramarine, cooler than royal, with the art-world specificity of a color owned, briefly, by one artist.
A vivid cool azure
Sits at OKLCH lightness 0.38, chroma 0.195, hue 263° — a vivid cool azure, the kind of color that earns its place loudly.
Dark enough to host white text comfortably for body copy; pure black on this background drops below the WCAG floor for anything but the largest display sizes.
Pairings + neighbors
Triadic counterparts sit at #a80030 and #30a800 — three slices of the wheel 120° apart, the classic balanced trio. The pairings stay in the vibrant register if all three keep their saturation; pull one toward neutral and the trio turns into a feature-with-supporting-cast.
The closest curated cousin in the library is Sapphire at #2138ab — a near-perceptual match (ΔE 5.4 in CIELAB). Worth the click if today's color almost works but you want to test a sibling.
Auto-composed from the etymology corpus and computed color properties · subject to revision