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Authoritative Atitlán

#644ca2
Notes

Authoritative Atitlán (#644CA2) 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 (257°, 36%, 47%) 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.

HEX
#644ca2
RGB
rgb(100, 76, 162)
HSL
hsl(257, 36%, 47%)
HWB
hwb(257 30% 36%)
OKLCH
oklch(48.4% 0.134 293.7)
HSV
hsv(257, 53%, 64%)
LAB
lab(38.70% 30.52 -43.27)
LCH
lch(38.70% 52.95 305.20)
CMYK
cmyk(38%, 53%, 0%, 36%)

Etymology

Authoritative
adjective

Latin auctōritāt-, authority — adjectival suffix -ive. As a color modifier, authoritative implies a saturated-and-formal-imperative quality where the hue carries decisional weight and institutional credibility. Sits at the bold-and-authoritative end of the grid, parallel to commanding and magisterial in usage.

Atitlán
noun

Mayan-named volcanic crater lake in Guatemala's western highlands, surrounded by Tolimán, San Pedro, and Atitlán volcanoes. The lake's depth and volcanic basement give it an unusual deep blue-violet at certain light angles. Atitlán color refers to Lake Atitlán surface at crepuscule in clear weather: a saturated, slightly cool deep blue-violet with the optical complexity of deep-water Rayleigh-scattered indigo light.

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

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Harmonies

Accessibility

Color-vision simulation

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.

#644ca2
Original
#285ca5
Protanopia
#2d5aa0
Deuteranopia
#555d6f
Tritanopia
#575757
Achromatopsia
WCAG contrast

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.

The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAon White
6.78:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AA Largeon Black
3.10:1

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