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Phosphorescent Hyssop Turquoise

#09ddd5
Notes

Phosphorescent Hyssop Turquoise (#09DDD5) 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 (178°, 92%, 45%) 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
#09ddd5
RGB
rgb(9, 221, 213)
HSL
hsl(178, 92%, 45%)
HWB
hwb(178 4% 13%)
OKLCH
oklch(81.0% 0.139 190.1)
P3
color(display-p3 0.3968 0.8538 0.8313)
HSV
hsv(178, 96%, 87%)
LAB
lab(79.94% -45.27 -8.72)
LCH
lch(79.94% 46.10 190.90)
CMYK
cmyk(96%, 0%, 4%, 13%)

Etymology

Phosphorescent
adjective

Greek phōsphóros, light-bringer — adjectival suffix -escent. As a color modifier, phosphorescent implies a saturated-and-cool-glow-after-stimulation quality, the bright cool-green-blue color of Cu-doped-ZnS glow-in-the-dark photoluminescent surfaces. Sits at the bright-and-cool end of the grid, parallel to fluorescent and luminous in usage.

Hyssop
modifier

Hebrew ēzōb, Biblical-purifying-herb. As a color modifier, hyssop implies a Biblical-purifying-herb-and-monastic-physic-garden quality, the visual register of monastic-physic-garden-and-Biblical-hyssop hand-Biblical-purifying-herb-and-monastic-physic-garden monastic-physic-garden-and-Biblical-hyssop-and-Cluniac-cloister hyssop-and-Biblical-purifying-herb surfaces under monastic-physic-garden-and-Biblical-hyssop-and-Cluniac-cloister Cluny-and-Saint-Gall-physic-garden monastic-physic-light. Sits at the modifier-and-flavor end of the grid, parallel to savory and balm 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.

#09ddd5
Original
#cfd1d5
Protanopia
#b7bfd6
Deuteranopia
#00e3da
Tritanopia
#afafaf
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
1.71:1
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
12.32:1

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
##09DDD5
Display P3
Display P3
color(display-p3 0.3968 0.8538 0.8313)
P3 has subtle headroomOKLCH chroma 0.139

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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