By the nineteenth and early twentieth centuries, the copying of famous works in museums was a standard part of artistic training across Europe. Students and professional copyists reproduced the Louvre’s major holdings as educational exercises and commercial commissions. The Mona Lisa was among the most frequently copied works. The museum kept records of copy licenses, and those records show a substantial number of authorized copies being made in the decades before the theft.
The Valfierno story — in which forged copies of the painting were allegedly sold to wealthy collectors as the genuine stolen original — exploits the existence of this copying tradition. If credible copies of the painting existed and could be presented to buyers who had no access to the authentic work for comparison, the scheme as described was theoretically possible. This is part of what makes the story superficially compelling.
But the story’s plausibility as an engineering problem is not the same as its historical truth. No buyer has ever come forward claiming to have been sold a fake Mona Lisa by Valfierno. No copy from the alleged six has been identified as such. No financial records of the alleged transactions have surfaced. The story is internally consistent but externally evidenceless.
The legitimate copies of the Mona Lisa that exist — in museums, private collections, and storage facilities around the world — are simply part of the history of artistic practice, made openly by known artists with no connection to the theft. Some of them are historically significant works in their own right. The Prado copy, in particular, has contributed genuinely to the scholarship of Leonardo’s original.