Certain Silk Brick
Certain Silk Brick (#AD1D3E) is a true red with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (346°, 71%, 40%) 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 teal. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin certus, fixed / sure — sharing root with English concern and certify. As a color modifier, certain implies a saturated-and-unambiguous quality where the hue declares its character without hesitation. Sits at the bold-and-confident end of the grid, parallel to assured and decisive in usage.
Old English sēolc, silk. As a color modifier, silk implies a smooth-and-lustrous-textile quality, the visual register of Chinese-Han-and-Italian-Renaissance-silk hand-reeled silk-fiber-and-mulberry-leaf-silkworm Han-and-Renaissance silk-textile surfaces under hand-reeled-silk-textile filtered light. Sits at the modifier-and-texture end of the grid, parallel to wool and lace in usage.
Fired clay, mineral red. The color refers to common building brick — iron-rich earthenware kilned to the specific dusky red-orange of a Victorian terrace, a Roman aqueduct, an adobe wall in New Mexico. Less saturated than ruby, warmer than burgundy, with a chalky cast that reads as architectural rather than decorative.
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.