Subterranean Suo
Subterranean Suo (#510138) is a deep magenta 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 (319°, 98%, 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 green. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin sub-terraneus, under-ground. As a color modifier, subterranean implies the cool deep darkness of cave-and-tunnel interiors where ambient daylight has been completely eliminated. Sits at the deep-and-cool end of the grid, where the hue reads as cellar-dwelling rather than night-sky deep.
Japanese 蘇芳, sappan-wood dye (Caesalpinia sappan) — derived from a Southeast Asian tree's heartwood, imported to Japan since the Nara period (710–794) for dyeing court robes a deep red-purple. Suo color refers to a suo-dyed Heian-period silk kinu: a saturated, slightly cool deep magenta with the silk luster of multi-bath sappan-wood dye on tussah silk. Distinct from akane (madder) and beni (safflower).
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.