Fluorescent Sepehr
Fluorescent Sepehr (#51ADFD) 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 (208°, 98%, 65%) 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 orange. 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 Persian word for firmament or celestial sphere — used in Persian Sufi poetry for the cosmic blue beyond the visible sky. Sepehr names the Persian astronomical concept of the seven heavens. The color refers to the Persian Sufi notion of sepehr-e jadid: a saturated, slightly cool very deep blue with the optical depth of upper-atmospheric scattering.
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.