Alexandrina Robertson Harris (July 11, 1886–February 1978) was a Scottish-born American painter of portrait miniatures.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Alexandrina_Robertson_Harris

Jacqueline Cochran by Alexandrina Robertson Harris
c.1950 / Watercolor on ivory / 3-1⁄2″x2-3⁄4″ / Smithsonian American Art Museum, DC

Alexandrina Robertson Harris on Pennsylvania Academy of Fine Arts

More links:
https://americanart.si.edu/artist/alexandrina-robertson-harris-2084
https://www.brooklynmuseum.org/opencollection/objects/92531
http://fineartdatabase.org/alexandrina-robertson-harris-1886-1978/

Marie-Victoire Jaquotot (January 15, 1772-April 27, 1855) was a 19th-century French painter.
Biography on Wikipedia: https://en.wikipedia.org/wiki/Marie_Victoire_Jaquotot

Casket for Louis XVIII’s snuffbox also contained painted miniatures to be fitted successively into the lid of the snuffbox. They were painted by Marie-Victoire Jaquotot. Details, description here:
https://www.louvre.fr/en/oeuvre-notices/casket-louis-xviiis-snuffbox

Marie Victoire Jaquotot on Artnet: http://www.artnet.com/artists/marie-victoire-jaquotot/

Further reading:
https://www.oxfordartonline.com/groveart/
Marie Victoire Jaquotot
https://www.sothebys.com/en/auctions/ecatalogue/2013/old-master-paintings-n08952/lot.287.html