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Smoldering Plasma Ultramarine

#405cbc
Notes

Smoldering Plasma Ultramarine (#405CBC) 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 (226°, 49%, 49%) 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
#405cbc
RGB
rgb(64, 92, 188)
HSL
hsl(226, 49%, 49%)
HWB
hwb(226 25% 26%)
OKLCH
oklch(50.6% 0.154 268.2)
P3
color(display-p3 0.2743 0.3578 0.7129)
HSV
hsv(226, 66%, 74%)
LAB
lab(41.80% 21.14 -53.77)
LCH
lch(41.80% 57.78 291.46)
CMYK
cmyk(66%, 51%, 0%, 26%)

Etymology

Smoldering
adjective

The progressive participle of smolder, to burn slowly without flame. Used as a color word since the late nineteenth century for the deep reds and oranges of barely-flame coal — the warm saturated darks where the heat is internal rather than emitted. Sits in the bold-and-warm corner, slightly less luminous than burning and slightly less calm than rich.

Plasma
modifier

Greek πλάσμα, something-molded-or-formed. As a color modifier, plasma implies an ionized-and-fourth-state-and-stellar-glow quality, the visual register of solar-corona-and-fluorescent-plasma hand-ionized-and-fourth-state-and-stellar-glow solar-corona-and-fluorescent-and-neon-tube plasma-and-ionized-and-fourth-state surfaces under solar-corona-and-fluorescent-and-neon-tube laboratory-and-stellar-and-aurora ionized-glow-light. Sits at the modifier-and-cosmic end of the grid, parallel to corona and nova 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.

#405cbc
Original
#2469bf
Protanopia
#005dba
Deuteranopia
#007283
Tritanopia
#5d5d5d
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
6.04:1
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
3.48:1

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
##405CBC
Display P3
Display P3
color(display-p3 0.2743 0.3578 0.7129)
P3 has subtle headroomOKLCH chroma 0.154

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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