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Spectral Procyon Turquoise

#21dacc
Notes

Spectral Procyon Turquoise (#21DACC) is a true cyan with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (175°, 74%, 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 red. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#21dacc
RGB
rgb(33, 218, 204)
HSL
hsl(175, 74%, 49%)
HWB
hwb(175 13% 15%)
OKLCH
oklch(80.2% 0.136 186.5)
P3
color(display-p3 0.4058 0.8425 0.7982)
HSV
hsv(175, 85%, 85%)
LAB
lab(78.94% -45.48 -5.38)
LCH
lch(78.94% 45.80 186.74)
CMYK
cmyk(85%, 0%, 6%, 15%)

Etymology

Spectral
adjective

Latin spectrum, appearance — adjectival suffix -al. As a color modifier, spectral implies a saturated-and-rainbow-decomposed-and-pure quality, the bright color of Newton-prism sunlight-decomposed seven-color spectrum band. Sits at the bright-and-pure end of the grid, parallel to prismatic and pure in usage.

Procyon
modifier

Greek προκύων, before-the-dog. As a color modifier, procyon implies a Canis-Minor-and-bright-foretaste-of-Sirius quality, the visual register of Canis-Minor-Procyon-and-Winter-Triangle hand-Canis-Minor-and-bright-foretaste-of-Sirius Canis-Minor-Procyon-and-Winter-Triangle-and-Bortle-1-sky procyon-and-Canis-Minor-and-bright-foretaste surfaces under Canis-Minor-Procyon-and-Winter-Triangle-and-Bortle-1-sky January-and-February-winter-zenith winter-stellar-light. Sits at the modifier-and-cosmic end of the grid, parallel to rigel and altair in usage.

Turquoise
noun

The hydrated copper-aluminum phosphate mined in Persia and the American Southwest for thousands of years — the firuze of Iran, the chalchihuitl of Mesoamerica, the heart of Pueblo and Navajo silverwork. The color refers to a fine Sleeping Beauty turquoise from Arizona: a saturated, slightly green-shifted blue with the slight matrix of host-rock veining. Brighter than persian, lighter than cerulean.

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.

#21dacc
Original
#cecdcc
Protanopia
#b7bcce
Deuteranopia
#00dfd5
Tritanopia
#b2b2b2
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).
Failon White
1.76:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAAon Black
11.97:1

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
##21DACC
Display P3
Display P3
color(display-p3 0.4058 0.8425 0.7982)
P3 has subtle headroomOKLCH chroma 0.136

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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