The signature is that of Franz Till of Dresden, who Blattel advises was active around 1866. Blattel notes that he was known for portraits on porcelain, copies, and photographs.
Blattel makes a further note; "Porcelain Painting Company: Vienna and Meissen style". Thus it is not clear if perhaps, Franz Till started as an individual painter, and then grew into a company which was active for the remainder of the 19C.
There is another miniature on porcelain in this collection of a girl which is also signed "F Till Dresden", see View
The portraits may be painted by copying a photograph, or they may be painted over a faint photographic base, in a manner similar to the way Matthieu De Roche painted over a faint photographic base, but which was on an enamel on copper ground.
Two large porcelain plaques signed "F Till Dresden" are shown here. They were sold at auction recently, the boy (10in x 7.5in) for $4300 and the nun (12.72in x 7.5in) for $5000. No doubt there are many more.
So far no on-line articles have been found which discuss the painting of portraits on porcelain like these examples.
Any references or more information about the process would be welcome, as it seems that the subject is much under-researched.
Unfortunately, little is known of the sitter, but a flavour of her privileged environment can be gained from the following references.
The only fact the vendor (a descendent of Dr Erhard Hartung von Hartungen) knew, was that the sitter had been a patient of Dr. Erhard Hartung von Hartungen at his very famous and elegant homoeopathic sanatorium. This specialised in treating nervous dieseases at Riva am Gardasee, (now Riva del Garda) and was at the northern lake end of a lake which in the extreme north of Italy. Before World War I much of the area was owned by the Hapsburg family, but they had to cede it after the end of the war.
There is a 1995 book about the Sanitorium; "Ai confini della Mitteleuropa: Il Sanatorium von Hartungen di Riva del Garda : dai fratelli Mann a Kafka gli ospiti della cultura europea" by Albino Tonelli. (I think this translates as "On the shores of Middle Europe: The Von Hartungen Sanatorium on the Garda River: the hosts of European culture, from the Mann children to Kafka".)
There is an interesting series of photographs of five generations of the Von Hartungen family at homeoint.org/photo/
At The Cambridge Companion to Kafka - Google Books Result it is commented that a reference to the Sanatorium run by Dr Von Hartungen in a book by the famous author Franz Kafka is one of the very few references in Kafka's work where he can be seen alluding to a real locale and a real event. The event being the suicide of retired Major-General Ludwig von Koch of the Austrian army, on 3 October, 1913 when Kafka was visiting the Sanatorium during the months of September and October 1913.
The famous German author Thomas Mann also stayed at the Sanatorium for six weeks in 1901, see VQR » Why Thomas Mann Wrote as did Sigmund Freud. 1284