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 replicas and reinterpretations
In 2011, the Prado museum in Madrid, Spain, announced discovery of what may be the earliest known replica.
Miguel Falomir, heading the Department of Italian Renaissance Painting at the time of the discovery, stated the Prado "had no idea of (the painting's) significance" until a recent restoration.
Recovered from the Prado's vaults, the replica – which El Mundo newspaper dubbed ""Mona Lisa"'s twin" ("above, far right") – was reportedly painted simultaneously alongside Leonardo as he painted his own "Mona Lisa"; in the same studio, by a "key" student.
It was painted on walnut. The replica has been part of the Prado's collection since the museum's founding in 1819.