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Ironclad Column Ultramarine

#313a99
Notes

Ironclad Column Ultramarine (#313A99) is a true blue 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 (235°, 51%, 40%) 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.

HEX
#313a99
RGB
rgb(49, 58, 153)
HSL
hsl(235, 51%, 40%)
HWB
hwb(235 19% 40%)
OKLCH
oklch(40.2% 0.153 273.2)
P3
color(display-p3 0.1989 0.2264 0.5781)
HSV
hsv(235, 68%, 60%)
LAB
lab(29.36% 28.33 -53.14)
LCH
lch(29.36% 60.22 298.07)
CMYK
cmyk(68%, 62%, 0%, 40%)

Etymology

Ironclad
adjective

English compound iron + clad — referring to the 19th-century USS-Monitor and CSS-Virginia iron-armored warships. As a color modifier, ironclad implies a saturated-and-armored-and-impenetrable quality where the hue carries the visual weight of forged-iron armor-plate. Sits at the bold-and-fortified end of the grid, parallel to fortified and armored.

Column
modifier

Latin columna, column. As a color modifier, column implies a vertical-Doric-and-Ionic-and-Corinthian quality, the visual register of Greek-and-Roman-Column hand-cut Doric-Ionic-Corinthian fluted-and-capital classical-column architectural surfaces under Greek-and-Roman classical-column architectural light. Sits at the modifier-and-architecture end of the grid, parallel to pillar and plinth in usage.

Ultramarine
noun

The pigment ground from lapis lazuli — the Afghan mineral imported through Venice in the late Middle Ages, more expensive by weight than gold during the Renaissance. The color refers to a freshly mixed ultramarine pigment in linseed oil: a saturated, slightly violet-shifted deep blue with the matte finish of micron-ground rock. Deeper than cobalt, cooler than royal, with the art-historical weight of the blue Vermeer reserved for Mary's robe.

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.

#313a99
Original
#004a9c
Protanopia
#004197
Deuteranopia
#005264
Tritanopia
#3f3f3f
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
9.56:1
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
2.20:1

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
##313A99
Display P3
Display P3
color(display-p3 0.1989 0.2264 0.5781)
P3 has subtle headroomOKLCH chroma 0.153

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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