Regal Celtic Ultramarine
Regal Celtic Ultramarine (#4A7BFE) is a true azure with a neon character. It sits at the high-saturation edge of its family. Use it sparingly, as signage, accent, or highlight against darker surfaces. Its HSL profile (224°, 99%, 64%) places it in the highly saturated band at a mid 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 amber. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin rēgālis, kingly — derived from rēx (king). As a color modifier, regal implies a saturated-and-royal-formality quality, the deep-rich color of British-Coronation-period royal vestment-and-mantle and Imperial-State-Crown regalia. Sits at the bold-and-imperial end of the grid, parallel to sovereign and royal in usage.
Latin Celticus, of-the-Celts. As a color modifier, celtic implies a knotwork-and-La-Tène quality, the visual register of Irish-and-Welsh-and-Scottish Celtic-knotwork hand-carved bronze-and-stone metalwork-and-illuminated-manuscript surfaces under Celtic-Irish-Welsh-Scottish illuminated-manuscript-tradition light. Sits at the modifier-and-cultural end of the grid, parallel to norse and welsh in usage.
The pigment ground from lapis lazuli — the Afghan mineral imported through Venice in the late Middle Ages, more expensive by weight than gold during the Renaissance. The color refers to a freshly mixed ultramarine pigment in linseed oil: a saturated, slightly violet-shifted deep blue with the matte finish of micron-ground rock. Deeper than cobalt, cooler than royal, with the art-historical weight of the blue Vermeer reserved for Mary's robe.
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 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.