A retiree found a 530-year-old sketch by Leonardo da Vinci and it's already worth $21 million

Leonardo headTajanThe study of Christian martyr St. Sebastian.

A 530-year-old sketch by Leonardo da Vinci has just been uncovered in France. The Parisian auction house Tajan unveiled it this week, and immediately valued it at 15 million euros ($21 million), according to the New York Times.

The drawing was made with pen and ink and is only 7.5 x 5 inches in size. It is believed to be one of eight studies representing “The Martyred Saint Sebastian” listed in da Vinci’s Codex Atlanticus notebooks. Art historians speculate that da Vinci finished a painting of St. Sebastian, but it has yet to be discovered.

This sketch only came to light when a retired French doctor found it among his late father’s papers.

“I had a sense that it was an interesting 16th-century drawing that required more work,” Thaddée Prate, director of old master pictures at the Tajan auction house, told the New York Times. He asked for a second opinion from an expert in old master drawings Patrick de Bayser, who noticed that the sketches were accompanied by notes written in Renaissance Italian by someone who was left handed, which da Vinci was.

Leonardo 1TajanThe full version of the sketch.

For a final and third opinion, Prate went to Carmen C. Bambach, a curator of Italian and Spanish drawings at the Metropolitan Museum of Art.

“The attribution is quite incontestable,” she said in a phone interview to the New York Times. “What we have here is an open-and-shut case. It’s an exciting discovery.”

Leonardo 2TajanTwo scientific studies that were also found.

This discovery is the first in over 15 years of a work by da Vinci, so it’s no surprise that the tiny sketches are valued so highly.

According to French laws, the Louvre Museum can propose a “fair international market value” to buy the drawing and keep it in France where it was discovered. If that doesn’t happen, Quartz reports that a public auction is expected in June 2017.

NOW WATCH: A space engineer explains why humans will never go past Mars

Business Insider Emails & Alerts

Site highlights each day to your inbox.

Follow Business Insider Australia on Facebook, Twitter, LinkedIn, and Instagram.