Oil on Ceramic. She is one of the paintings in the “Gallery of Beauties” (or Schönheit—short for Schönheintengalerie (as it is written in the middle on the back of the painting) in Munich, Germany: http://en.wikipedia.org/wiki/Gallery_of_Beauties
These paintings were copied over and over for decorative purposes throughout the rest of the 19th century and sold all over the world. As it says on the top—“Helen Müller geb (abreviation for “born” in German) Sedlemayer”—your painting is a copy on ceramic of Helen Sedlmayer: