The technique of colouring is wonderful, and so are the detail and the composition, but the proportions of the face are off... The face is much bigger than the head, so the woman looks unnatural.
Also the head is too round, it is like she does not have a chin or any structure for her jaws and a forhead, unfortunately it reminds me of a balloon. I would advice to make a realistic skull study for future references. maybe even several from different angles, and to learn head proportions.
But this is the only thing you really need to work on, the technique is amazing.
I hope you are not offended, that was not my intention. I just tried giving some constructive feedback, different than another:"beautiful" comment.
Still, don't get me wrong it is a beautiful work overall.