Placid Arch Ocean
Placid Arch Ocean (#18819F) is a true cyan 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 (193°, 74%, 36%) 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 red. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin placidus, gentle / quiet — derived from placēre (to please). As a color modifier, placid implies a clear-and-unruffled quality where the hue carries the visual register of mirror-smooth lake-surface in windless mid-morning. Sits at the crisp-and-calm end of the grid, parallel to serene and peaceful in usage.
Latin arcus, bow / curve. As a color modifier, arch implies a Roman-and-Gothic-and-Romanesque-vault quality, the visual register of Roman-aqueduct-and-Romanesque-cathedral hand-cut stone-and-brick voussoir-and-keystone arch-and-vault architectural surfaces under monumental architecture light. Sits at the modifier-and-architecture end of the grid, parallel to dome and vault in usage.
The body of saltwater that covers seventy percent of Earth's surface — a single connected mass divided by convention into Atlantic, Pacific, Indian, Southern, and Arctic. The color refers to the average reflectance of mid-depth temperate ocean: a saturated, slightly green-shifted deep blue with the optical depth of a body of water that absorbs all light below the photic zone. Deeper than mediterranean, cooler than peacock.
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.