Oh, Ok I see better now. This looks to be quite a low quality render, what are your settings? Final? And yes, I think this comes from the ambient lighting. In this case, I would crank up the GI slider to +1, or add a small point light to light up the face, and move the ambient/sunlight slider a bit over the sun (even if there is no sun, this will allow Vue to take the light coming from the point light to be used in the lighting solution) And I'd recommend radiosity for this.