Severe Tarbuttite
Severe Tarbuttite (#42219C) 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 (256°, 65%, 37%) 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 sevērus, strict / serious. As a color modifier, severe implies a deep-and-uncompromising-formal quality, the dark plain-textile color of Cistercian and Calvinist anti-decorative interior aesthetic. Sits at the deep-and-formal end of the grid, parallel to austere and stern in tone.
Rare zinc-phosphate mineral first described from the Broken Hill lead-zinc deposits of Zambia in 1907, also found at Reaphook Hill in South Australia. Tarbuttite color refers to a deep-violet Broken Hill tarbuttite crystal cluster: a saturated, slightly cool deep blue-violet with the glassy finish of zinc-phosphate mineral. Named for Percy Coventry Tarbutt, an early-20th-century mining-company director.
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.