Mix in sintering cobalt(II) monoxide with alumina at 1200 °C, you'd get a blue pigment called 'cobalt'. The color cobalt is one of the oldest blues in history, known for its cool and less intense shade. In the history of man, it's the color used to draw decorations and coloring agent in ceramics and porcelain. It dates way back to the late 8th century or early 9th century.
However, cobalt only became official much later on. it was French chemist Louis Jacques Thénard who independently discovered pure alumina-based cobalt pigment in 1802,
Cobalt is a favorite among artists. In fact, Engilsh watercolorist John Varley had once suggested.that cobalt blue is a good substitution for ultramarine when painting the skies. You've probably been enchanted by the mesmerizing canvas of "Starry Night", the captivating little girl dressed in blue in "A Girl with a Watering Can", or the stunning cobalt found in the "Monet's Garden" series. Since Thénard's discovery, painters such as Pierre-August Renoir, Claude Monet, J. M. W. Turner and Vincent Van Gogh have been using the pigment generously.
In aesthetics and color meanings, Lifewire sees cobalt as a color of sky, nature, and water. Like most blues, it's a friendly, peaceful and soothing color; but cobalt is more suggestive with richness.
For photography, cobalt blue is one of the most challenging colors to reproduce. According to researcher Robin D. Myers' paper on color accuracy, the color cobalt shows up more accurately when the image was shot in low light or when other colors are incorrectly reproduced, and this applies to both film and digital photography. To reproduce a cool cobalt with a simple blue subject, it is recommended to use fluorescent lighting combined with low and minimal red and infrared emissions to reduce the blue from being ultramarine. Take inspiration from National Geographic's Life in Color: Blue series for hints of cobalt.