Crepuscular Susa
Crepuscular Susa (#5C1B97) is a true indigo 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 (271°, 70%, 35%) 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 lime. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin crepusculāris, of twilight — derived from crepusculum (twilight). As a color modifier, crepuscular implies the deep blue-violet darkness of civil-twilight period between sunset and nightfall. Sits at the deep-and-cool end of the grid, where the hue carries the Belt of Venus atmospheric-scattering quality of clear-sky horizon at dusk.
Persian Achaemenid winter capital — and the imperial court color storehouse for Tyrian purple tribute textiles imported from Phoenician Tyre and Sidon under Darius I (522–486 BCE). Susa color refers to a Susa-stored Achaemenid royal kandys coat: a saturated, slightly cool deep violet with the matte finish of multi-bath shellfish-dye on Persian-court silk-and-wool blend.
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.
This color is chromatic enough that authoring it as P3 native (instead of clamping to sRGB) gives a perceptibly more saturated render on wide-gamut displays — modern Macs, iPhones, iPads, and most recent OLED laptops.