Refulgent Tonbo
Refulgent Tonbo (#4491FB) 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 (215°, 96%, 63%) 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 refulgēns, shining-back — present-participle of refulgere, sharing root with fulgor (lightning). As a color modifier, refulgent implies a saturated-and-reflective-shining quality, the bright color of polished-bronze-and-armor reflective-surface mid-day-sun reflection. Sits at the bright-and-saturated end of the grid, parallel to effulgent and resplendent in usage.
The Japanese word for dragonfly — and tonbo-iro, the iridescent blue-green of dragonfly wing membranes. Tonbo is also a samurai-era heraldic motif representing victory (katsumushi, victory-insect). The color refers to a male blue-tail dragonfly's abdomen at rest: a saturated, slightly cool iridescent deep blue with the satin finish of structurally colored insect cuticle.
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.