This piece is unbelievably amazing. Everything about it is exceptionally well done: The grey background not only heightens the "silver" sensation of the artwork, but it also creates a soft, yet cool and metallic tone that works very well. The proportions of the face are spot-on, and the expression is excellent. I think my favorite aspects of the piece are the eyes and the hair - oh my goodness! The way the hair captures the light, and that confident look in the eyes: sheer magnificence.
Seriously, this piece is near perfect... I only have two real issues. Firstly, the edge of the right cheek against the background doesn't look as smooth as it should; it seems rather bumpy and uneven. Secondly, although the hand is fantastic, the colors could be blended a little more to create a more natural look - the way you did so well with the face. (In fact, the area on the front of the hand between the thumb and the forefinger has an unfinished look to it that appears rather odd when compared to the rest of the piece.) But those are my only two gripes
Overall, I adore this piece. The tone is marvelous, the detail is great, and I could look at that hair and that face all day Keep up the fabulously awesome work!!!