Fluorescent Coreopsis
Fluorescent Coreopsis (#C9CE53) is a true yellow with a warm character. It leans warm, pulling light toward red, orange, and yellow. Naturally inviting, it suits editorial and hospitality contexts. Its HSL profile (62°, 56%, 57%) 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 blue. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Latin fluēre, to flow — adjectival suffix -escent. As a color modifier, fluorescent implies a saturated-and-UV-stimulated-glow quality, the bright color of fluorite-and-ZnS mineral-pigment fluorescent-lamp emission. Sits at the bright-and-cool end of the grid, parallel to phosphorescent and neon in usage.
The genus Coreopsis — North American composite-family annuals (also called tickseed) whose bright yellow ray flowers fill prairie restorations and pollinator gardens. The color refers to a C. tinctoria bloom: a saturated, slightly red yellow with the matte finish of multi-rayed composite 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.