Stygian Prussian
Stygian Prussian (#1A4378) 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 (214°, 64%, 29%) places it in the balanced band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. For a confident two-color system, pair it with its complementary orange. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
From the Greek Styx, the river of the underworld — used as an adjective in English since the seventeenth century to mean infernally dark. Stygian is the literary register for absolute darkness, deeper than inky and warmer than vantablack. Almost always reaches for poetic weight rather than precise reflectance.
The first modern synthetic blue pigment — accidentally produced in 1704 by Berlin alchemist Johann Jacob Diesbach when contaminated potash turned a red dye unexpectedly blue. The result was Berlin blue (also Prussian blue): a saturated, slightly green-shifted deep blue with the matte finish of a pigment more lightfast than indigo and far cheaper than ultramarine. Cooler than cobalt, deeper than navy, with the art-historical weight of the pigment used in Hokusai's Great Wave.
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.