Robust Sumi
Robust Sumi (#3F4FD5) is a true blue with a cool character. It leans cool, sitting on the blue, green, and violet side of the wheel. Quiet and dependable, a fit for product UI and data visualization. Its HSL profile (234°, 64%, 54%) 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 amber. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
From the Latin robustus, of oak — implying strength combined with substance. As a color modifier, robust describes saturation combined with body: a robust burgundy, a robust olive. Sits in the bold-and-warm corner alongside strong and solid, with the slightly textural implication of a color that has substance behind the pigment.
Japanese ink stick, made from soot of pine resin or sesame oil mixed with animal-glue binder, used in sumi-e brush painting and shodō calligraphy. Although nominally black, undiluted sumi on rice paper carries a deep blue-violet undertone. Sumi color refers to a heavily-loaded sumi brushstroke: a saturated, slightly cool deep blue-violet with the matte finish of pine-soot ink on absorbent washi.
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.