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Sure Cope Verdigris

#21b3b5
Notes

Sure Cope Verdigris (#21B3B5) 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 (181°, 69%, 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 red. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#21b3b5
RGB
rgb(33, 179, 181)
HSL
hsl(181, 69%, 42%)
HWB
hwb(181 13% 29%)
OKLCH
oklch(69.8% 0.113 196.4)
P3
color(display-p3 0.3363 0.6917 0.7039)
HSV
hsv(181, 82%, 71%)
LAB
lab(66.44% -34.63 -11.45)
LCH
lch(66.44% 36.48 198.30)
CMYK
cmyk(82%, 1%, 0%, 29%)

Etymology

Sure
adjective

Old French seur, certain — used as a color modifier since the medieval period for hues that read as confident and stable. Sure red, sure blue: moderate saturation combined with optical commitment. Sits at the crisp-bucket center alongside steady and true.

Cope
modifier

Latin cappa, long-ecclesiastical-cloak. As a color modifier, cope implies a long-ecclesiastical-cloak-and-bishop's-cope quality, the visual register of Anglican-and-Catholic-bishop's-cope hand-long-ecclesiastical-cloak-and-bishop's-cope Anglican-and-Catholic-bishop's-cope-and-Westminster-and-Vatican cope-and-long-ecclesiastical-cloak surfaces under Anglican-and-Catholic-bishop's-cope-and-Westminster-and-Vatican Westminster-Abbey-and-Sistine-Chapel ecclesiastical-cloak-light. Sits at the modifier-and-textile end of the grid, parallel to cloak and cape in usage.

Verdigris
noun

The basic copper carbonate that forms on weathered copper and bronze — the pigment scraped from oxidized metal and used in Renaissance painting before being supplanted by more stable greens. The color refers to a thick verdigris on aged copper roofing or the Statue of Liberty's surface: a soft, slightly muted blue-green with the powdery finish of mineral oxide. Cooler than patina, warmer than seafoam, with the archaeological weight of a mineral made by time.

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.

#21b3b5
Original
#a6aab5
Protanopia
#929bb6
Deuteranopia
#00b9b3
Tritanopia
#949494
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
2.57:1
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
8.18:1

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
##21B3B5
Display P3
Display P3
color(display-p3 0.3363 0.6917 0.7039)
P3 has subtle headroomOKLCH chroma 0.113

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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