Maria Feodorovna wore her hair curly almost always and she was often photographed wearing lace-trimmed collars.
From tumblr.com-tagged-maria-feodorovna.
This is probably the dress seen in this image and this image.
Keywords: 1870, Malenkaya-Glosoli, Maria Feodorovna (1847-1928), Prinsesse Dagmar, Princess Dagmar, Dagmar (kejserinde af Rusland), Marie Sophie Frederikke Dagmar, Мария Фёдоровна (жена Александра III), Glucksberg family, Romanov family, Princess, Empress, Russian, curly coiffure, chemisette, high neckline, ruff, brooch, lace-edged fichu, nows, vee neckline, close sleeves, cuffs