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Defined Umber Lagoon

#10b5db
Notes

Defined Umber Lagoon (#10B5DB) is a true cyan with a neon character. It sits at the high-saturation edge of its family. Use it sparingly, as signage, accent, or highlight against darker surfaces. Its HSL profile (191°, 86%, 46%) places it in the highly saturated band at a mid lightness. Best used in small doses, like logos, CTAs, focus rings, or highlight text, where its saturation becomes a feature rather than noise. 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
#10b5db
RGB
rgb(16, 181, 219)
HSL
hsl(191, 86%, 46%)
HWB
hwb(191 6% 14%)
OKLCH
oklch(71.6% 0.129 220.4)
P3
color(display-p3 0.3251 0.6992 0.8426)
HSV
hsv(191, 93%, 86%)
LAB
lab(68.22% -24.41 -29.71)
LCH
lch(68.22% 38.45 230.60)
CMYK
cmyk(93%, 17%, 0%, 14%)

Etymology

Defined
adjective

Latin dēfīnīre, to set bounds — past-participle of define. As a color modifier, defined implies a clear-and-edge-distinct-and-precise quality where the hue carries the visual register of sharp-bounded-and-clearly-delimited surface. Sits at the crisp-and-clear end of the grid, parallel to crisp and sharp in usage.

Umber
modifier

Latin umbra, shadow. As a color modifier, umber implies a shadowed-and-Umbrian-earth-pigment quality, the visual register of Caravaggio-and-Rembrandt-umber hand-shadowed-and-Umbrian-earth-pigment Caravaggio-and-Rembrandt-and-Vermeer-Dutch-Golden-Age umbered-and-shadowed-and-deep-glazed surfaces under Caravaggio-and-Rembrandt-and-Vermeer chiaroscuro-and-tenebrist-and-glazed studio-window-light. Sits at the modifier-and-mood end of the grid, parallel to shade and gloom in usage.

Lagoon
noun

A shallow body of saltwater partially or fully enclosed by a barrier — coral atoll lagoons in the Pacific, Venice's Laguna Veneta, the Florida Keys' backcountry. The color refers to the average reflectance of a calm tropical lagoon at midday: a saturated, slightly muted blue-green with the optical clarity of shallow water over white sand. Brighter than reef, cooler than aquamarine, with the postcard weight of a Pacific atoll seen from above.

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.

#10b5db
Original
#9eb0dd
Protanopia
#869fdb
Deuteranopia
#00c1c1
Tritanopia
#959595
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
2.43:1
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
8.65:1

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
##10B5DB
Display P3
Display P3
color(display-p3 0.3251 0.6992 0.8426)
P3 has subtle headroomOKLCH chroma 0.129

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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