Rendez-Blue

#abbed0

A blue that is nearly neutral — the hue shows only against a true grey. It is light — black text sits on it comfortably, white text does not.

Hex

#abbed0

RGB

171, 190, 208

OKLCh

79.3% 0.033 246.8°

CIELAB (D50)

75.9, -3.9, -11.4

What is true of this colour, and of no other

13 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 uses only 30% of the chroma available at this lightness and hue — there is a far more vivid version of this colour inside sRGB.
As text on white it measures APCA Lc 36.4; on black, Lc -66.1. 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 8.9 and 9.4 and 11.0 — no red cone.

Text on this colour

White text

1.91:1 — fails AA

Black text

11.01:1 — passes AA

Black text is the better of the two at11.01:1. That is enough for body text.

As text on white, it needs to change

#677989 is the nearest colour of the same hue that passes AA on white, at 4.50:1. Only the lightness moved.

Try it against your own background

The same colour, with one cone missing

As you see it

#abbed0

protanopia

#bcbcd0 · ΔE00 8.9

deuteranopia

#b9b9d0 · ΔE00 9.4

tritanopia

#b5b5fa · ΔE00 11.0

Run a whole palette through all three

The twelve nearest named colours

Ranked by CIEDE2000 — perceptual distance, not hex arithmetic. The closest isAirway at ΔE00 0.89: below 1.0 — an ordinary observer cannot tell these apart, even side by side. What the numbers mean.

AirwayΔE00 0.89 · #aec1d4
Wood PigeonΔE00 0.985 · #aabbcc
SkywayΔE00 1.211 · #a6bbcf
Glacier MistΔE00 1.245 · #aabccb
Sweet BlueΔE00 1.63 · #aebed2
Blue ThistleΔE00 1.655 · #adc0d6
Cerulean TintΔE00 1.655 · #acbfcd
Faded IndigoΔE00 1.761 · #b2c4d4
ElevatedΔE00 1.79 · #b3c3d4
Time TravelΔE00 1.798 · #b3c4d5
Northern PondΔE00 1.808 · #a3b9cd
Paris GreyΔE00 1.909 · #a6b7c8

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