Practical Tsuyukusa
Practical Tsuyukusa (#818DB0) is a true 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 (225°, 23%, 60%) places it in the muted band at a mid lightness. It works across type, buttons, and borders, saturated enough to feel deliberate but balanced enough to not fight the rest of the palette. For a confident two-color system, pair it with its complementary amber. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Greek praktikós, practical — adjectival suffix -al. As a color modifier, practical implies a clear-and-purpose-fit-and-everyday quality where the hue carries the visual register of Shaker-and-Quaker utilitarian-and-functional everyday-life craft. Sits at the crisp-and-functional end of the grid, parallel to functional and workmanlike in usage.
Commelina communis, the Japanese dayflower — a wildflower whose deep blue flowers were used in the seventeenth century as a textile dye and aobana paper for yuzen dyeing patterns. Tsuyukusa-iro (露草色) refers to the saturated blue of fresh dayflower. The color refers to a fresh dayflower bloom: a saturated, slightly cool deep blue with the satin finish of three-petaled flower.
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.
This color sits well within the sRGB cube. P3 and sRGB share the gray axis and most desaturated tones, so a P3 display renders this identically to an sRGB display.