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Vaulted Slate

#17378a
Notes

Vaulted Slate (#17378A) is a deep 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 (223°, 71%, 32%) places it in the balanced band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. 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
#17378a
RGB
rgb(23, 55, 138)
HSL
hsl(223, 71%, 32%)
HWB
hwb(223 9% 46%)
OKLCH
oklch(37.0% 0.144 264.4)
HSV
hsv(223, 83%, 54%)
LAB
lab(26.01% 21.34 -49.43)
LCH
lch(26.01% 53.84 293.36)
CMYK
cmyk(83%, 60%, 0%, 46%)

Etymology

Vaulted
adjective

Old French voulte, vault via Latin volūta (rolled) — past-participle of vault. As a color modifier, vaulted implies the deep-and-architectural-and-Gothic quality of Salisbury-Cathedral-and-Chartres-Cathedral nave-vault overhead-stone-arched ceiling. Sits at the deep-and-architectural end of the grid, parallel to cavernous with cathedral-vault register.

Slate
noun

A fine-grained metamorphic rock formed from compressed shale — fissile, durable, and the standard roofing material for Welsh and Vermont houses since the nineteenth century. The color refers to a freshly split piece of Welsh slate: a soft, slightly muted gray-blue with the matte finish of a layered mineral cleavage. Cooler than steel, lighter than navy, with the architectural weight of a roof material that lasts a hundred years.

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.

#17378a
Original
#00438d
Protanopia
#003888
Deuteranopia
#004c5b
Tritanopia
#363636
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
10.77:1
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
1.95:1

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