Sturdy Phthalo
Sturdy Phthalo (#0B59A1) is a deep azure 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 (209°, 87%, 34%) places it in the highly saturated band at a dark 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
Old French estourdi, stunned, reckless — drifted in English to mean robust, well-built. Used as a color modifier since the seventeenth century for hues that read as durable and unfussy — the working browns of saddle leather, the working greens of pasture wool. Sits in the bold-and-warm corner alongside robust and solid.
Phthalocyanine pigment — a synthetic copper-organic compound introduced in 1936. Phthalo Blue (PB15) is among the most lightfast and saturated blues available to modern artists. The color refers to fresh Phthalo Blue watercolor on white paper: a saturated, slightly cool deep blue-green with the matte finish of organic-pigment-and-binder.
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.