Towering Indaco
Towering Indaco (#181B5C) is a deep blue with a cool character. It leans cool, sitting on the blue, green, and violet side of the wheel. Quiet and dependable, a fit for product UI and data visualization. Its HSL profile (237°, 59%, 23%) 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 tour, tower via Latin turris — present-participle of tower. As a color modifier, towering implies a deep-and-vertical-and-architectural quality, the dark cool-gray of Salisbury-Cathedral-and-Chartres-Cathedral spire-and-tower against the sky. Sits at the deep-and-architectural end of the grid, parallel to imposing and looming.
The Italian word for indigo — borrowed via Greek indikon (Indian thing). Indaco in Italian art vocabulary refers specifically to the deep-blue plant-dye pigment used in Italian Renaissance painting for the Marian mantles and aristocratic dress. The color refers to indaco pigment in tempera: a saturated, slightly cool deep blue. The Italian cousin of indigo.
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.