Dark Cyan

#008b8b

A cyan that is muted. It is mid — the hardest range to put text on, either colour struggles.

Hex

#008b8b

RGB

0, 139, 139

OKLCh

57.6% 0.098 194.8°

CIELAB (D50)

51.9, -32.3, -9.5

What is true of this colour, and of no other

14 other named colours sit within ΔE00 2 of it — this part of the space is crowded, and the names here are finer distinctions than most people make.
It sits exactly on the sRGB boundary: at this lightness and hue the gamut has nothing left, and a wider display would show a more colourful version of it.
As text on white it measures APCA Lc 67.9; on black, Lc -33.7. The sign is the polarity, which the WCAG ratio discards.
Built into an eleven-step scale, 10 of the 10 adjacent pairs stay ΔE00 2 apart — see the ramp.
protanopia and deuteranopia and tritanopia shift it by ΔE00 24.5 and 25.7 and 34.3 — no red cone.

Text on this colour

White text

4.15:1 — large text only

Black text

5.07:1 — passes AA

Black text is the better of the two at5.07:1. That is enough for body text.

As text on white, it needs to change

#008585 is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved, and some saturation was given up to stay inside sRGB.

Try it against your own background

The same colour, with one cone missing

As you see it

#008b8b

protanopia

#84848b · ΔE00 24.5

deuteranopia

#76768c · ΔE00 25.7

tritanopia

#6565ff · ΔE00 34.3

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isMarrs Green at ΔE00 0.357: below 1.0 — an ordinary observer cannot tell these apart, even side by side. What the numbers mean.

Marrs GreenΔE00 0.357 · #008c8c
Egyptian TealΔE00 0.541 · #008c8d
Forever TealΔE00 1.069 · #018e8e
Green MoblinΔE00 1.082 · #008888
Corfu ShallowsΔE00 1.116 · #008e8d
DuvallΔE00 1.301 · #0f8b8e
Old TruckΔE00 1.334 · #0a888a
Industrial BlueΔE00 1.352 · #00898c
Tubbataha TealΔE00 1.439 · #0e8787
Greenish BlueΔE00 1.546 · #0b8b87
Well BlueΔE00 1.565 · #00888b
India BlueΔE00 1.589 · #008a8e

12 of these have no page of their own: pages exist for the 4,961 colours the dataset marks as good names.