The 110,000 euro cost of the renewed search will be paid for by authorities in Florence.
If the researchers find bones, they will be sent to experts at the University of Bologna, who will attempt to conduct carbon dating tests and extract DNA.
That material will then be compared with DNA from the remains of Gherardini’s children, who are buried in a church in Florence.
The archaeologists’ ultimate aim is to find enough skull fragments to be able to reconstruct her face, enabling a direct comparison to be made with the Mona Lisa.
That could solve a mystery which has intrigued art historians for centuries – who exactly posed for the world’s best known painting, which hangs in the Louvre Museum in Paris.
“All the existing documents point to the fact that Lisa Gherardini was the main model for the Mona Lisa between 1502 and 1503,” said Silvano Vinceti, the head of the National Committee for the Preservation of Cultural Heritage, who is involved in the dig.
Gherardini was the wife of Francesco Del Giocondo, and the Mona Lisa is known in Italian as La Gioconda.