The dressing table of Rose Selfridge (Frances O’Connor) is quite busy. She’s clearly a fan of Guerlain perfumes: two flacons montre  can be seen on the shelf in front of the window, but there’s more. She opens a Guerlain box, decorated with people and animals, and takes out a flacon bouchon coeur, the bottle with the heart-shaped stopper designed by Raymond Guerlain in collaboration with Baccarat. It would be easy to assume this is Après l’Ondée, created by Jacques Guerlain in 1906, but it’s not, because that perfume has never had that bottle. It would have been a historically accurate choice (this episode takes place in 1909), but prop masters opted for something different. The flacon bouchon coeur originally contained three perfumes, released between 1912 and 1919.
L’Heure Bleue was created by Jacques Guerlain in 1912. I don’t think this is the perfume seen on Rose’s dressing table because of the blue lettering on the central sticker.
The last possibility is Mitsouko, one of the most famous perfumes by the French brand. Another creation by Jacques Guerlain, it was launched in 1919, ten years after the time in which the tv show is set.
My guess is that the perfume seen in this episode is Fol Arôme, because the pale orange decorations on the sticker seem to match.
 The flacon montre was first released in 1936. The presence of these bottles in this episode is totally inaccurate, but no one can deny their decorative function.