I didn't know that this shade of color actually still falls under "purple." Does it have a specific name?
So from my initial impression, the closest colors I picked up were bluish shades of "imperial purple" or "royal violet/indigo", which I saw as a possible nod towards the cultivation and production of "Tyrian purple" in Mogador.
After taking another look at her art, I see that the blue portion of the Tricolore motifs on her uniform appears to be a similar (albeit darker) shade as the rest of the top, which at that point it would probably be fair for it to be somewhat "midnight blue" or darker shades of "royal blue".
Personally, I see it more on the purple/violet/indigo spectrum. Bluish shades of Tyrian purple and darker shades of what we would call royal blue were being made at the time as well, so it's still up there.