Sterile Zǐ
Sterile Zǐ (#58446D) is a true indigo with an earthy character. It leans grounded and natural, the kind of color that plays well with wood, clay, linen, and warm neutrals. Its HSL profile (269°, 23%, 35%) places it in the muted 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 sterilis, barren / not-fertile — sharing root with Greek steiros (barren). As a color modifier, sterile implies a clear-and-medical-clean-and-stripped quality, the crisp color of operating-theater surgical-environment white-and-stainless-steel surfaces. Sits at the crisp-and-clean end of the grid, parallel to sanitary and hygienic in usage.
Chinese 紫, purple — the imperial court color of the Tang and Song dynasties, derived from Lithospermum erythrorhizon (gromwell) and overdyed with Polygonum tinctorium. Zǐ color refers to a Tang-dynasty imperial robe field: a saturated, slightly cool deep violet with the silk luster of multi-bath gromwell-root-and-indigo overdye on tussah silk. Cooler than zǐsè (formal deep purple).
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 sits well within the sRGB cube. P3 and sRGB share the gray axis and most desaturated tones, so a P3 display renders this identically to an sRGB display.