Cobalt blue
| Cobalt blue | |
|---|---|
A sample of a commercial cobalt blue pigment
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 Color coordinates |
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| Hex triplet | #0047AB |
| sRGBB (r, g, b) | (0, 71, 171) |
| CMYKH (c, m, y, k) | (0.17, , , ) |
| HSV (h, s, v) | (215°, 100%, 67%) |
| Source | [Unsourced] |
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B: Normalized to [0–255] (byte) H: Normalized to [0–100] (hundred) |
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Cobalt blue is a blue pigment made by sintering cobalt(II) oxide with alumina at 1200 °C. Chemically, cobalt blue pigment is cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl2O4. Cobalt blue is lighter and less intense than the (iron-cyanide based) pigment Prussian blue. It is extremely stable and has historically been used as a coloring agent in ceramics (especially Chinese porcelain), jewelry, and paint. Transparent glasses are tinted with the silica-based cobalt pigment smalt.
Cobalt blue in impure forms had long been used in Chinese porcelain, but it was independently discovered as a pure alumina-based pigment by Louis Jacques Thénard in 1802. Commercial production began in France in 1807. The first recorded use of cobalt blue as a color name in English was in 1777. The leading world manufacturer of cobalt blue in the 19th century was Benjamin Wegner's Norwegian company Blaafarveværket, ("blue colour works" in Dano-Norwegian). Germany was also famous for production, especially the blue colour works (Blaufarbenwerke) in the Ore Mountains of Saxony.
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