My Favorite Blues
Here are my favorite set of blues ranging from blue purple to blue green.
Maya blue (Natural Pigments) is a lovely low chroma dark blue that adds opacity and easily lowers chroma and value in the blue hue range when needed.
Natural Pigments also has wonderful Ultramarine blues with thixotropic properties. (A thixotropic paint is one that as you move it mechanically it becomes less viscous and when you stop it becomes more viscous again.) Michael Harding also has a wonderful ultramarine blue that I use frequently.
Cobalt blue by Vasari and Cerulean Blue from Michael Harding are also indispensable.
And finally... Caribbean Blue from Old Holland. It is a wonderful variant of pthalo blue that yields amazing clean teal hues.