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Certain Seth Cerulean

#2584c7
Notes

Certain Seth Cerulean (#2584C7) is a true azure with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (205°, 69%, 46%) 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 orange. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#2584c7
RGB
rgb(37, 132, 199)
HSL
hsl(205, 69%, 46%)
HWB
hwb(205 15% 22%)
OKLCH
oklch(59.2% 0.133 244.8)
P3
color(display-p3 0.2629 0.5103 0.7592)
HSV
hsv(205, 81%, 78%)
LAB
lab(52.97% -3.30 -42.34)
LCH
lch(52.97% 42.46 265.55)
CMYK
cmyk(81%, 34%, 0%, 22%)

Etymology

Certain
adjective

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.

Seth
modifier

Egyptian Set, god-of-storms-and-desert-chaos. As a color modifier, seth implies a desert-storm-and-chaos-god quality, the visual register of Egyptian-Seth-and-Ombos-temple hand-desert-storm-and-chaos-god Egyptian-Seth-and-Ombos-temple-and-Osirian-conflict seth-and-desert-storm-and-chaos-god surfaces under Egyptian-Seth-and-Ombos-temple-and-Osirian-conflict Western-Desert-and-storm-cloud red-desert-storm-light. Sits at the modifier-and-myth end of the grid, parallel to horus and ptah in usage.

Cerulean
noun

From the Latin caeruleum, originally referring to dark blue paint pigment of the Roman world, then via French céruléen into English. As a modern art-supply name, cerulean blue is the cobalt-tin oxide pigment introduced in 1805. The color refers to a clean, slightly green-shifted blue with the matte finish of mineral pigment in linseed oil: lighter than cobalt, deeper than aqua, with the painter's weight of a word for sky.

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.

#2584c7
Original
#6486ca
Protanopia
#4d78c6
Deuteranopia
#00949c
Tritanopia
#757575
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).
AA Largeon White
4.04:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAon Black
5.20:1

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
##2584C7
Display P3
Display P3
color(display-p3 0.2629 0.5103 0.7592)
P3 has subtle headroomOKLCH chroma 0.133

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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