That stunning picture is 40.3 cm wide and 54.8 cm high, oil on walnut board. Unfortunately, the original background has been overlaid probably in the 17th century.
The subject of the portrait is identified as Cecilia Gallerani, and was probably painted at a time when she was the mistress of Lodovico Sforza, Duke of Milan and Leonardo was in the service of the Duke.
Lady with an Ermine has been heavily over painted. The entire background was darkened, her dress below the ermine was retouched and a transparent veil being worn by the woman was repainted to match the colour of her hair. The result of this last retouching has been to give the appearance that her hair reaches down and underneath her chin. Yet another change was the addition of dark shadows between the fingers of her right hand, a close look at the bottom two fingers shows they are quite inferior to the others after an unknown restorer repainted them. An x-ray of this painting revealed the presence of a door in the original background.
Leonardo's Lady with an Ermine is one of the most important works in all of Western art. Only a handful of authentic panel painting of him survive. Enormously curious, Leonardo often painted with experimental materials or abandoned projects once he had mastered the formal challenge each presented.
An object of the greatest rarit, the Lady with an Ermine is a captivating image of exquisite elegance and reveals the artistic genius of Leonardo da Vinci's incomparable creative mind.
According to www.leonardodavinci.net