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Rich Tang Cerulean

#0189d4
Notes

Rich Tang Cerulean (#0189D4) 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 (201°, 99%, 42%) 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
#0189d4
RGB
rgb(1, 137, 212)
HSL
hsl(201, 99%, 42%)
HWB
hwb(201 0% 17%)
OKLCH
oklch(60.7% 0.149 243.9)
P3
color(display-p3 0.2339 0.5290 0.8081)
HSV
hsv(201, 100%, 83%)
LAB
lab(54.71% -3.29 -46.96)
LCH
lch(54.71% 47.08 265.99)
CMYK
cmyk(100%, 35%, 0%, 17%)

Etymology

Rich
adjective

Old French riche, wealthy, abundant — applied to color since the medieval period for hues that read as plentiful in pigment. Rich red, rich brown: the implication is depth combined with saturation, a color that gives the eye more to absorb. Sits at the saturated mid-light corner of the engine's grid, slightly warmer than bold and deeper than vivid.

Tang
modifier

Old Norse tangi, sharp-projecting-taste. As a color modifier, tang implies a sharp-and-projecting-and-bright-bite quality, the visual register of Atlantic-and-Hebridean-sea-tang hand-sharp-and-projecting-and-bright-bite Atlantic-and-Hebridean-sea-tang-and-tide-pool-bite tang-and-sharp-and-projecting surfaces under Atlantic-and-Hebridean-sea-tang-and-tide-pool-bite Outer-Hebrides-and-North-Cornish-tide-pool sharp-bite-light. Sits at the modifier-and-flavor end of the grid, parallel to zest and tart 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.

#0189d4
Original
#648cd7
Protanopia
#487bd3
Deuteranopia
#009ba4
Tritanopia
#727272
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
3.80:1
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
5.53:1

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
##0189D4
Display P3
Display P3
color(display-p3 0.2339 0.5290 0.8081)
P3 has subtle headroomOKLCH chroma 0.149

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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