It's the copy of the world's most famous smile.

This replica of Leonardo Da Vinci's Mona Lisa temporarily joined her sister in the Louvre museum in Paris.

Although it's made by one of Da Vinci's assistants, the copy teaches a great deal about the original, according to the museum.

Vincent Delieuvin is the curator for paintings at the Louvre.

SOUNDBITE: The Louvre Museum Curator for Paintings, Vincent Delieuvin, saying (French)

"We discover here the whole perspective of the landscape, in the (original) Mona Lisa we thought that the perspective was out of line, had no structure, that the vanishing point on the right was higher than on the left, and here in the Prado's Mona Lisa we discover our own original piece with a continuous perspective line."

The replica is on loan from Madrid's Prado museum, as part of the Louvre's exhibit that explores Da Vinci's creative process.

At its center is this work titled "The Virgin and Child with Saint Anne."

SOUNDBITE: The Louvre Museum Curator for Paintings, Vincent Delieuvin, saying (French)

"The "Saint Anne," which is the last painting by Leonardo Da Vinci, is a project on which he worked for 20 years. Twenty years of meditation, of perfecting the project and it's the only piece in Leonardo's career which allows us to retrace the whole continuity of his work."

The detailed documentation of the work's progress includes sketches and studies by both Leonardo and his students.

Put together as the exhibit "Saint Anne, the last masterpiece by Leonardo Da Vinci", it opens to the public on March 29 and will run until the end of June.

Elly Park, Reuters.