Cobalt is a divine color and there is nothing as fine for putting an atmosphere round things. Carmine is the red of wine and is warm and lively like wine. The same goes for emerald green too. It's false economy to dispense with them, with those colors. Cadmium as well.
Vincent van Gogh (2014). “Delphi Complete Works of Vincent van Gogh (Illustrated)”, p.2552, Delphi Classics