This is one of my favorite portraits. The artist is Jean-Etienne Liotard. The artist was born in Geneva, Switzerland to French parents. Jean-Etienne Liotard used pastels to create his artwork. His paintings can be found in museums in Amsterdam, Geneva and the Louvre in France. The Frick Collection in New York has hosted an exhibit featuring this artist in the past.
The Portrait of a Young Woman was painted some time in the late 18th century. The portrait is currently in the Saint Louis Art Museum in Missouri and there is some speculation that Jean-Etienne Liotard did not paint this portrait. I am not sure how the museum came to this conclusion after the portrait has been attributed to Jean-Etienne after so many years. If anyone reading this has more information about this painting, I would love to hear it.