Resolute Rhine
Resolute Rhine (#437FCF) is a true azure 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 (214°, 59%, 54%) places it in the balanced 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 orange. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
From the Latin resolutus, unwavering — used as a color modifier in literary contexts for hues that read as committed and unmoving. Resolute blue, resolute green: the saturation is full, the hue holds its position without shifting under different light. Sits in the bold-bucket center alongside strong and true, with slightly more focus on stability than presence.
The Rhine River — Europe's third-longest, flowing from the Swiss Alps to the Dutch North Sea. Rhine color refers to mid-depth Rhine River water at Lorelei on the Mittelrhein: a saturated, slightly cool deep blue with the optical depth of Alpine-glacier-fed European river water.
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.