As far as I know, there is no magic dividing line between student grade and artist grade. Student grade paints are usually characterized by very low prices due to less actual pigment in the tube - and substituting the higher priced pigments - like cadmiums and cobalts - with cheaper alternatives (usually labeled as hues). As Janet has mentioned, the pigment load reportedly falls between their traditional artist and student grade lines. The Artisans do have real cadmiums and cobalts (and cerulean, too)! In my mind, this makes them artist grade with no reason not to use them.
Don