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.
Speculations about Mona Lisa
It has for a long time been argued that after Leonardo's death the painting was cut down by having part of the panel at both sides removed. Early copies depict columns on both sides of the figure. Only the edges of the bases can be seen in the original. However, some art historians, such as Martin Kemp, now argue that the painting has not been altered, and that the columns depicted in the copies were added by the copyists. The latter view was bolstered during 2004 and 2005 when an international team of 39 specialists undertook the most thorough scientific examination of the "Mona Lisa" yet undertaken. Beneath the frame (the current one was fitted to the "Mona Lisa" in 2004) there was discovered a "reserve" around all four edges of the panel. A reserve is an area of bare wood surrounding the gessoed and painted portion of the panel. That this is a genuine reserve, and not the result of removal of the gesso or paint, is demonstrated by a raised edge still existing around the gesso, the result of build up from the edge of brush strokes at the edge of the gesso area.