Certain Indygo
Certain Indygo (#5C59E2) is a true blue with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (241°, 70%, 62%) 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 yellow. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin certus, fixed / sure — sharing root with English concern and certify. As a color modifier, certain implies a saturated-and-unambiguous quality where the hue declares its character without hesitation. Sits at the bold-and-confident end of the grid, parallel to assured and decisive in usage.
Polish for indigo (Indigofera tinctoria) — adopted into Polish color terminology during the 18th-century Polish-Lithuanian Commonwealth's textile-trade contact with Ottoman indigo merchants. Indygo color refers to a freshly indygo-dyed Polish-folk linen: a saturated, slightly cool deep blue-violet with the matte finish of multi-bath fermentation indigo on hand-spun linen. Cooler than English indigo and warmer than Russian fioletovyy.
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.