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Praetorian Niger

#0666b1
Notes

Praetorian Niger (#0666B1) is a true azure 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 (206°, 93%, 36%) places it in the highly saturated band at a mid 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 orange. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#0666b1
RGB
rgb(6, 102, 177)
HSL
hsl(206, 93%, 36%)
HWB
hwb(206 2% 31%)
OKLCH
oklch(50.3% 0.142 250.5)
HSV
hsv(206, 97%, 69%)
LAB
lab(42.33% 4.60 -46.58)
LCH
lch(42.33% 46.81 275.63)
CMYK
cmyk(97%, 42%, 0%, 31%)

Etymology

Praetorian
adjective

Latin praetōriānus, of the praetor — adjectival suffix, referring to the Roman-Imperial elite guard-cohorts. As a color modifier, praetorian implies a saturated-and-elite-and-imperial-guard quality, the deep-rich color of Roman-Praetorian-Guard elite-imperial-bodyguard scarlet-tunic-and-bronze-armor military-formation. Sits at the bold-and-formal end of the grid, parallel to spartan and imperial.

Niger
noun

The third-longest river in Africa — flowing through Guinea, Mali, Niger, Benin, and Nigeria to the Gulf of Guinea. Niger color refers to mid-depth Niger River water at Timbuktu in Mali: a saturated, slightly cool deep blue-brown with the optical complexity of West African inland-delta river water.

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.

#0666b1
Original
#3f6bb4
Protanopia
#205eb0
Deuteranopia
#007883
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
5.93:1
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
3.54:1

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