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Bold Throb Ultramarine

#0051c3
Notes

Bold Throb Ultramarine (#0051C3) 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 (215°, 100%, 38%) 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 amber. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#0051c3
RGB
rgb(0, 81, 195)
HSL
hsl(215, 100%, 38%)
HWB
hwb(215 0% 24%)
OKLCH
oklch(47.0% 0.191 259.9)
HSV
hsv(215, 100%, 76%)
LAB
lab(37.52% 25.51 -64.89)
LCH
lch(37.52% 69.72 291.46)
CMYK
cmyk(100%, 58%, 0%, 24%)

Etymology

Bold
adjective

Old English beald, brave, courageous — a quality word that crossed over to color in the late seventeenth century. Bold describes a color that asserts itself: high saturation combined with mid lightness, where the hue presents itself without compromise. Sits at the center of the bold-bucket grid, near strong and rich. Closer to a presence word than a pigment word.

Throb
modifier

Middle English throbben, to-beat-strongly. As a color modifier, throb implies a pulsing-and-beating-and-rhythmic quality, the visual register of racing-pulse-and-temple-throb hand-pulsing-and-beating-and-rhythmic racing-pulse-and-temple-throb-and-heartbeat throbbed-and-pulsing-and-beating-and-rhythmic surfaces under racing-pulse-and-temple-throb-and-heartbeat fevered-and-quickened-and-rhythmic candlelit-bedside-light. Sits at the modifier-and-mood end of the grid, parallel to pang and pulse 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.

#0051c3
Original
#0061c7
Protanopia
#0050c1
Deuteranopia
#006e82
Tritanopia
#484848
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
7.08:1
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
2.96:1

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