Isleworth Mona Lisa
According to Leonardo's early biographer Giorgio Vasari, Leonardo had started to paint "Mona Lisa" in 1503, but "left it unfinished". However, a fully finished painting of a "certain Florentine lady" surfaced again in 1517, shortly before Leonardo's death and in his private possession. The latter painting almost certainly is the one that now hangs in the Louvre. Based on this contradiction, supporters of the authenticity of the "Isleworth Mona Lisa" claim it is the unfinished "Mona Lisa", made at least partially by Leonardo, and the Louvre "Mona Lisa" a later version of it, made by Leonardo for his own use.
Mona Lisa
The "Mona Lisa" has survived for more than 500 years, and an international commission convened in 1952 noted that "the picture is in a remarkable state of preservation." This is partly due to a variety of conservation treatments the painting has undergone. A detailed analysis in 1933 by Madame de Gironde revealed that earlier restorers had "acted with a great deal of restraint." Nevertheless, applications of varnish made to the painting had darkened even by the end of the 16th century, and an aggressive 1809 cleaning and revarnishing removed some of the uppermost portion of the paint layer, resulting in a washed-out appearance to the face of the figure. Despite the treatments, the "Mona Lisa" has been well cared for throughout its history, and although the panel's warping caused the curators "some worry", the 2004–05 conservation team was optimistic about the future of the work.