National Geographic has a nice article about trying to authenticate a lost portrait presumed to be the handiwork of Leonardo da Vinci.
The work appeared at an auction at Christie’s in 1998 for $21,850. The catalog listed no artist name and said the portrait was early 19th Century and German. The dealer Kate Ganz bought it, and it was later purchased in her gallery by Canadian collector Peter Silverman. Here’s National Geographic:
Silverman emailed a digital image of Bianca to Martin Kemp. Emeritus professor of art history at Oxford University and a renowned Leonardo scholar, Kemp regularly receives images, sometimes two a week, from people he calls “Leonardo loonies,” convinced they have discovered a new work. “My reflex is to say, No!” Kemp told me. But the “uncanny vitality” in the young woman’s face made him want a closer look. He flew to Zurich, where Silverman kept the drawing in a vault. At 13 by 9¾ inches, it is roughly the size of a legal pad. “When I saw it,” Kemp said, “I experienced a kind of frisson, a feeling that this is not normal.”