Portrait of a Commander Being Dressed for Battle, a painting attributed to the 17th-century Flemish Baroque artist Sir Peter Paul Rubens and valued at over $13 million, was sold by Princess Diana’s family at a Christie’s auction house just last week. Art historians and critics, however, began to publicly question its authenticity. Brian Sewell, an art historian and the London Evening Standard’s art critic, told The Independent it’s “an uncomfortable Rubens. It’s one of those pictures that doesn’t quite ring true.” A spokesman for Christie’s claims the work is real. The art house conducted rigorous research, the spokesman said, and an academic panel vouched for it. The painting’s provenance, though, has never been agreed upon: Prior to World War II, the painting had been considered a work by Pourbus, a contemporary of Rubens, but since then, it’s been considered a true Rubens. Experts believe it will take years, if ever, to come to a definitive conclusion. In the meantime, the anonymous buyer should consider it a bargain: according to Sewell, “I think anything under 20 million is cheap for a Rubens."