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Robust Thaw Sapphire

#303aa7
Notes

Robust Thaw Sapphire (#303AA7) is a true blue with an earthy character. It leans grounded and natural, the kind of color that plays well with wood, clay, linen, and warm neutrals. Its HSL profile (235°, 55%, 42%) 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 yellow. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#303aa7
RGB
rgb(48, 58, 167)
HSL
hsl(235, 55%, 42%)
HWB
hwb(235 19% 35%)
OKLCH
oklch(41.4% 0.173 272.2)
P3
color(display-p3 0.1958 0.2263 0.6306)
HSV
hsv(235, 71%, 65%)
LAB
lab(30.51% 33.24 -59.74)
LCH
lch(30.51% 68.37 299.09)
CMYK
cmyk(71%, 65%, 0%, 35%)

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.

Thaw
modifier

Old English thawian, to-melt-or-soften. As a color modifier, thaw implies a spring-melt-and-softening-frost quality, the visual register of English-spring-and-Pennine-thaw hand-spring-melt-and-softening-frost English-spring-and-Pennine-thaw-and-Cumbria-Highland-thaw thaw-and-spring-melt-and-softening-frost surfaces under English-spring-and-Pennine-thaw-and-Cumbria-Highland-thaw Yorkshire-Dales-and-Lake-District-and-Cairngorm spring-melt-light. Sits at the modifier-and-weather end of the grid, parallel to slush and rain 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.

#303aa7
Original
#004daa
Protanopia
#0042a5
Deuteranopia
#00566b
Tritanopia
#404040
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
9.17:1
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
2.29:1

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
##303AA7
Display P3
Display P3
color(display-p3 0.1958 0.2263 0.6306)
P3 has subtle headroomOKLCH chroma 0.173

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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