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Robust Tooled Sapphire

#375ac6
Notes

Robust Tooled Sapphire (#375AC6) is a true blue with a cool character. It leans cool, sitting on the blue, green, and violet side of the wheel. Quiet and dependable, a fit for product UI and data visualization. Its HSL profile (225°, 57%, 50%) 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 amber. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#375ac6
RGB
rgb(55, 90, 198)
HSL
hsl(225, 57%, 50%)
HWB
hwb(225 22% 22%)
OKLCH
oklch(50.5% 0.173 266.6)
HSV
hsv(225, 72%, 78%)
LAB
lab(41.53% 24.72 -60.05)
LCH
lch(41.53% 64.94 292.38)
CMYK
cmyk(72%, 55%, 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.

Tooled
modifier

Old French tōl, implement. As a color modifier, tooled implies a hand-worked-and-detailed quality, the visual register of Renaissance-and-Florentine-tooled-leather hand-worked-and-stamped-and-engraved tooled-leather-and-bookbinding-and-saddle-and-belt hand-worked surfaces under Renaissance-and-Florentine hand-tooled-leather workshop-light. Sits at the modifier-and-texture end of the grid, parallel to carved and inlaid 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.

#375ac6
Original
#0069ca
Protanopia
#005cc4
Deuteranopia
#007487
Tritanopia
#5a5a5a
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
6.10:1
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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