She stands next to a table with a fan in her left hand, wearing a low cut black dress showing her pale skin.  
The subject of this painting was painted twice more, by Gustave Courti and Antonio de la Gandara, seven and fourteen years later, respectively.  In the original, the light source is from the right, accentuating a little jewel in the subject's red hair and the shoulder straps on her dress.   She stands next to a table with a fan in her left hand, wearing a low cut black dress showing her pale skin.  Perhaps to shield the subject from the foreseen controversy, the artist withheld her real name, Gautreau, from the painting's title.  FTP who is this woman, subject of an 1884 portrait by John Singer Sargent?
The subject of this painting was painted twice more, by Gustave Courti and Antonio de la Gandara, seven and fourteen years later, respectively.  
Madame X