Mannerly Diabase
Mannerly Diabase (#09093B) is a deep blue 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 (240°, 74%, 13%) places it in the balanced band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. For a confident two-color system, pair it with its complementary yellow. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Old French manere, manner / way — adjectival suffix -ly. As a color modifier, mannerly implies a neutral-and-polite-and-formal quality where the hue carries the visual register of Edwardian-and-Belle-Époque polite-and-formal-and-mannerly interior-decoration-and-dress-attire coordinated-color tone. Sits at the neutral-and-friendly end of the grid, parallel to courteous and polite in usage.
French diabase, traverse-mineral — the deep-cool-gray fine-grained intrusive-igneous rock of dyke-and-sill emplacement, particularly the Triassic-and-Jurassic Newark-Basin diabase of the New York-and-New Jersey Palisades. Diabase color refers to a New-Jersey-Palisades Newark-Basin diabase cliff-face in midday sun: a dark cool-gray with the matte finish of plagioclase-and-pyroxene intrusive-igneous fine-grained rock.
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 exploreHarmonies
Accessibility
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.
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.
Wide gamut
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.
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.