The Hermitage lists this as "Portrait of a Young Woman." However Dru identified the sitter as Grand Princess Maria Mikhailovna in a posting to the Alexander Palace Time Machine Discussion Forum of 27 September 2011 and another poster agreed with some doubt. I cannot find a biographical article for her.
This work appears to be unfinished, the background was not over-painted in an oval all around, although a guideline was made and much of the oval was completed. I filled in the unfinished background with Photoshop.