This is such a powerful piece. She looks very said but also like she is contemplating something. The realism is dead on and absolutely stunningly gorgeous. I like how you can see the textures in the face. Her eyes are very lovely as well. For a sad piece the hair seems a bit wild so it sort of contradicts it a bit, but the hair does look very real and fantastic. Your background is simple and blends in with her clothing so it does not take away from her one bit.
This is amazing, you did a great job, keep it up~!
I haven't much to add to what MandieEllie commented.
I would say, however, that the difference of tones across her skin contributes to the dark setting ; and that the curve of her lips, also contribute to the expressed sadness. The makeup staints are perfect.
This is a woman, and what we feel is that this is both a beautiful, and strong of character woman, struck by terrible sadness. Her eyes cry but she still seems to "stand up". This is what makes the expressed sadness even deeper, and with much more accentuating that it could have been otherwise.
Thanks for sharing this art. This contributed to make me send you a note!