Must be Leonardo's work.
Who else could have painted an image of that quality at that time?
Even Raphael was not capable. His comparable works in the same period to me look far inferior.
Has to be Leo. I agree. In which case it must be the original La Gioconda. Which rather turns my art world upside down.
http://blog.zap2it.com/pop2it/2012/09/the-isleworth-mona-lisa-were-there-two-versions-of-the-leonardo-da-vinci-masterpiece.html
Not comfortable disagreeing with my one time teacher Martin Kemp. But there you go.
I concede that the later Mona Lisa employs a higher quality of brushwork. But if it is genuine, the Isleworth is clearly an earlier version and therefore it is likely that Leo was still acquiring his technique - the Isleworth is also prettier, more realistic looking and in better proportion (eg mouth vs face). One quality remarked upon re the ML was its realism. I think the Paris ML has to concede to the Isleworth on this measure.