If you can't tell a priceless work of art from an imitation, don't be discouraged—even experts at the world's top museums have been known to mistake a forgery for the real thing. That's a lesson the Terrus Museum in Elne, France recently learned the hard way when it found that 82 of the 140 paintings in its collection are fakes, as Co.Design reports.

Elne, a village in the South of France, is the hometown of painter Étienne Terrus, a late-19th century artist known for depicting local landscapes. The village has spent roughly $200,000 over the last 20 years buying the painter's supposed works for its art museum, which recently completed extensive renovations.

Ahead of its grand reopening, Terrus Museum guest curator Eric Forcada noticed something fishy about the collection: Some paintings contained landmarks that weren't supposed to be there. In one painting, Forcada spotted a building constructed in 1958, 36 years after Terrus's death. After calling in a panel of experts to examine the paintings more closely, the museum discovered that dozens of them were frauds.

The incident is a reflection of a larger trend troubling the art world. By one estimate, as much as 20 percent of artworks in major museums in the UK weren't made by the painters they're attributed to. Elne's expensive oversight shows just how hard it is to keep inauthentic paintings from ending up on gallery walls.

Forensic studies can shed light on a piece's origins, but older paintings caked with varnish are harder to examine. In some cases, researching and verifying a painting's history can save museums and art collectors buyer's remorse down the road, but this becomes an issue when buyers are looking at a rare piece that someone else might snatch up if they don't act fast. Rushing into an art purchase can lead to enormous financial loss. Last year, Leonardo da Vinci’s Salvator Mundi was purchased for a record-breaking $450 million at auction, even though some people in the art world believed it was fake, and therefore worthless.

When forged paintings do sneak their way into museums, they often go unnoticed by visitors. The difficulty of spotting fake paintings was even the subject of a game show that aired in the UK in 2016. Research by the show's creators found that people are particularly bad at identifying forged landscape paintings.

[h/t Co.Design]