The two small paintings are the smallest known portraits by the 17th-century Dutch master, who was best known for his much larger works.

An expert from the London auction house Christie’s found the two portraits, which probably date from 1635, quite by chance a few years ago during a routine inspection in the private collection of a British family. In his opinion, these were the last two known portraits of the Dutch master that were still in private ownership.

At an auction in July, the portraits were bought by the businessman Henry Holterman and his family, who have now made them available to the Rijksmuseum on permanent loan. “The Rijksmuseum has the largest and most representative Rembrandt collection in the world,” explained Holterman. “I feel like these works belong in the museum.”

Experts from the Rijksmuseum examined the paintings using X-rays and infrared radiation as well as color sample analysis to prove that the portraits were actually painted by Rembrandt. According to the museum, they were also painted in a style similar to other Rembrandt paintings from the same period, “particularly the construction of facial features and the loose brushwork.”