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Praetorian Spark Ruby

#a31b22
Notes

Praetorian Spark Ruby (#A31B22) is a true red 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 (357°, 72%, 37%) 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 cyan. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#a31b22
RGB
rgb(163, 27, 34)
HSL
hsl(357, 72%, 37%)
HWB
hwb(357 11% 36%)
OKLCH
oklch(46.4% 0.170 25.0)
P3
color(display-p3 0.5866 0.1631 0.1585)
HSV
hsv(357, 83%, 64%)
LAB
lab(35.38% 53.39 32.83)
LCH
lch(35.38% 62.68 31.59)
CMYK
cmyk(0%, 83%, 79%, 36%)

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.

Spark
modifier

Old English spearca, small-ember. As a color modifier, spark implies a small-bright-and-flying-ember quality, the visual register of blacksmith-anvil-and-bonfire-spark hand-small-bright-and-flying-ember blacksmith-anvil-and-bonfire-and-flint-strike sparked-and-small-bright-and-flying surfaces under blacksmith-anvil-and-bonfire-and-flint-strike orange-glow-and-iron-and-flint forge-and-hearth-light. Sits at the modifier-and-mood end of the grid, parallel to flash and flare in usage.

Ruby
noun

From the Latin ruber — simply, red. The gemstone is a chromium-tinged corundum, harder than anything in nature except diamond, and so saturated that a fine Burmese pigeon's blood ruby at auction outpaces a comparable diamond by weight. The color borrows the gem's confidence: a clear, glassy red without the brown of garnet or the blue of crimson.

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 explore

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.

#a31b22
Original
#484121
Protanopia
#695e1c
Deuteranopia
#b40020
Tritanopia
#383838
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).
AAAon White
7.67:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
Failon Black
2.74:1

Wide gamut

Display P3 representation

The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.

sRGB hex
sRGB hex
##A31B22
Display P3
Display P3
color(display-p3 0.5866 0.1631 0.1585)
P3 has subtle headroomOKLCH chroma 0.170

Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.

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