Smoldering Klein
Smoldering Klein (#3B5DDE) is a true blue with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (227°, 71%, 55%) places it in the balanced band at a mid lightness. It works across type, buttons, and borders, saturated enough to feel deliberate but balanced enough to not fight the rest of the palette. For a confident two-color system, pair it with its complementary amber. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
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.
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.
Closest matches
The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.
Variations
Click any swatch to exploreHarmonies
Accessibility
How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.
The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.