Australian art conservators have uncovered a rare portrait of an Italian Renaissance noblewoman. After several years of detective work, a 43-year mystery surrounding the painting has been cleared up.

Australian art conservators have uncovered a rare

portrait of an Italian Renaissance noblewoman.

The discovery was made by National Gallery of Victoria conservator Carl Villis. Villis has identified the subject and artist of the work, titled Portrait of a Youth, painted around 1520.

Villis says the painting, bought by the gallery in 1965, is by Renaissance artist Dosso Dossi. He says it is a portrait of Lucrezia Borgia... overturning a century of opinion that the painting is of a young man because the subject is holding a dagger.

Gallery director Gerard Vaughan says estimating how much the painting is worth would be an interesting process.

Gerard Vaughan said, "We will, if it is ever borrowed by another gallery somewhere in the world, we'll need to put insurance value on it before it can travel and that would be a most interesting process but we haven't got to that stage yet."

Technical analysis found the style and oval shape of the portrait matched the work of Dossi... who worked for the ruling family of Ferrara, where Borgia was Duchess from 1502 to 1519.

Lucrezia Borgia, daughter of Rodrigo Borgia who later ruled as Pope Alexander the Sixth, is one of the most famous women of Italian history.

Born into wealth and power in 1480, her name was linked to the murderous scheming and womanizing of her father and brother.

Lucrezia Borgia has been the subject of a 1833 play by Victor Hugo and a Donizetti opera.