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Plumb Boom Lagoon

#28b5db
Notes

Plumb Boom Lagoon (#28B5DB) 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 (193°, 71%, 51%) 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
#28b5db
RGB
rgb(40, 181, 219)
HSL
hsl(193, 71%, 51%)
HWB
hwb(193 16% 14%)
OKLCH
oklch(71.9% 0.124 221.5)
P3
color(display-p3 0.3483 0.6996 0.8427)
HSV
hsv(193, 82%, 86%)
LAB
lab(68.47% -22.97 -29.30)
LCH
lch(68.47% 37.24 231.91)
CMYK
cmyk(82%, 17%, 0%, 14%)

Etymology

Plumb
adjective

Latin plumbum, lead — referring to the lead-weighted plumb-line of pre-modern carpentry. As a color modifier, plumb implies a clear-and-vertical-true quality where the hue carries the visual register of gravity-aligned-and-perfectly-vertical surface. Sits at the crisp-and-balanced end of the grid, parallel to level and squared in usage.

Boom
modifier

Dutch boom, tree / spar. As a color modifier, boom implies a horizontal-spar-attached-to-mast quality, the visual register of Tall-Ship-and-yacht-boom hand-cut horizontal-spar-attached-to-mast-foot boom-and-mainsail tall-ship-and-yacht maritime-rigging surfaces under tall-ship-and-yacht boom-and-mainsail maritime light. Sits at the modifier-and-nautical end of the grid, parallel to spar and mast 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.

#28b5db
Original
#9fb0dd
Protanopia
#87a0db
Deuteranopia
#00c1c1
Tritanopia
#9a9a9a
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
2.41:1
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
8.72:1

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
##28B5DB
Display P3
Display P3
color(display-p3 0.3483 0.6996 0.8427)
P3 has subtle headroomOKLCH chroma 0.124

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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