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Robust Mull Sapphire

#175dc8
Notes

Robust Mull Sapphire (#175DC8) 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 (216°, 79%, 44%) 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
#175dc8
RGB
rgb(23, 93, 200)
HSL
hsl(216, 79%, 44%)
HWB
hwb(216 9% 22%)
OKLCH
oklch(50.2% 0.180 259.6)
HSV
hsv(216, 89%, 78%)
LAB
lab(41.50% 20.48 -61.30)
LCH
lch(41.50% 64.63 288.47)
CMYK
cmyk(89%, 53%, 0%, 22%)

Etymology

Robust
adjective

From the Latin robustus, of oak — implying strength combined with substance. As a color modifier, robust describes saturation combined with body: a robust burgundy, a robust olive. Sits in the bold-and-warm corner alongside strong and solid, with the slightly textural implication of a color that has substance behind the pigment.

Mull
modifier

Middle English mullen, to-grind-or-ponder. As a color modifier, mull implies a slow-pondered-and-warmed-and-spiced quality, the visual register of mulled-wine-and-mulled-thought hand-slow-pondered-and-warmed-and-spiced mulled-wine-and-mulled-cider-and-mulled-thought mulled-and-slow-pondered-and-warmed-and-spiced surfaces under mulled-wine-and-mulled-cider-and-mulled-thought clove-and-cinnamon-and-orange-peel hearth-side-winter-light. Sits at the modifier-and-mood end of the grid, parallel to muse and brood in usage.

Sapphire
noun

An iron-and-titanium-bearing corundum — the same mineral as ruby, hardness 9 on the Mohs scale, mined for two millennia from Sri Lanka, Burma, Madagascar, and the Cashmere mines of British India. The color refers to a fine Kashmir-cut sapphire: a saturated, slightly violet-shifted deep blue with the gem's signature internal velvet — a quality of light scattering in the stone that faceted glass cannot replicate. Cooler than cobalt, deeper than azure.

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.

#175dc8
Original
#006acc
Protanopia
#005ac6
Deuteranopia
#007889
Tritanopia
#565656
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).
AAon White
6.11:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AA Largeon Black
3.44:1

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