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Buttressed Susa

#870b7a
Notes

Buttressed Susa (#870B7A) is a deep violet with a jewel character. It carries the deep, saturated richness of a gemstone. Authoritative and slightly formal, it works well for type and heavy UI elements. Its HSL profile (306°, 85%, 29%) places it in the highly saturated band at a dark 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 green. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#870b7a
RGB
rgb(135, 11, 122)
HSL
hsl(306, 85%, 29%)
HWB
hwb(306 4% 47%)
OKLCH
oklch(43.3% 0.187 333.6)
P3
color(display-p3 0.4844 0.1078 0.4632)
HSV
hsv(306, 92%, 53%)
LAB
lab(31.34% 57.63 -30.15)
LCH
lch(31.34% 65.04 332.38)
CMYK
cmyk(0%, 92%, 10%, 47%)

Etymology

Buttressed
adjective

Old French bouterez, thrusting-mass — past-participle of buttress, derived from bouter (to thrust). As a color modifier, buttressed implies a saturated-and-architecturally-supported quality, the deep-rich color of Gothic-Cathedral flying-buttress-and-rib-vault stone-architecture. Sits at the bold-and-fortified end of the grid, parallel to fortified and reinforced.

Susa
noun

Persian Achaemenid winter capital — and the imperial court color storehouse for Tyrian purple tribute textiles imported from Phoenician Tyre and Sidon under Darius I (522–486 BCE). Susa color refers to a Susa-stored Achaemenid royal kandys coat: a saturated, slightly cool deep violet with the matte finish of multi-bath shellfish-dye on Persian-court silk-and-wool blend.

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.

#870b7a
Original
#023f7d
Protanopia
#3e5077
Deuteranopia
#8e1e47
Tritanopia
#2d2d2d
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).
AAAon White
8.90:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
Failon Black
2.36:1

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
##870B7A
Display P3
Display P3
color(display-p3 0.4844 0.1078 0.4632)
P3 has visible headroomOKLCH chroma 0.187

This color is chromatic enough that authoring it as P3 native (instead of clamping to sRGB) gives a perceptibly more saturated render on wide-gamut displays — modern Macs, iPhones, iPads, and most recent OLED laptops.

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