Plutonian Modré
Plutonian Modré (#031B4D) is a deep azure with a jewel character. It carries the deep, saturated richness of a gemstone. Authoritative and slightly formal, it works well for type and heavy UI elements. Its HSL profile (221°, 93%, 16%) places it in the highly saturated band at a dark lightness. Best used in small doses, like logos, CTAs, focus rings, or highlight text, where its saturation becomes a feature rather than noise. 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
From Pluto, the Roman god of the underworld (Greek Plouton). As a color modifier, plutonian implies the cool deep darkness of the underworld realms, with literary-classical register. Sits at the deep-and-cool end of the grid, parallel to Hadean and cooler than infernal.
The Czech word for blue — used for the saturated deep blue of Czech traditional Modrotisk (blue-print) folk-textile resist-dyeing. Modré covers the entire blue spectrum in Czech color vocabulary. The color refers to a freshly Modrotisk-printed cotton: a saturated, slightly cool deep blue with the matte finish of plant-dyed-resist-printed cotton.
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.
Wide gamut
The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.
Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.