Forgeries are as old as art itself, but impostors are having a field day in the age of the internet. Fortunately, art scholars, scientists and IT specialists are coming together to protect genuine art works and catch fraudsters.

In November last  year, a rediscovered painting by Leonardo da Vinci – fewer than 20 of which survive – set a new record at auction. "Salvator Mundi", a depiction of Jesus Christ, was the first authenticated Da Vinci painting to come to market in more than 100 years. It fetched $450.3 million at Christie's in New York, making it the most expensive work of art ever sold.

But when the portrait was acquired in 2005, its authorship was unknown. It was only after careful restoration that museums and Da Vinci scholars hailed the portrait as a prodigal son returning to the Old Master's fold. The portrait's journey from obscurity to fame, and the breathtaking sum it fetched, are illustrative of how the $45 billion fine art market has become a game of ever higher stakes. No sooner had the gavel landed that doubts began to be cast about the portrait's authenticity

Insatiable demand and dizzy prices bring out the forgers

Billionaires from Russia, China and newly emerging markets have joined established collectors in search of trophies and investment yield to drive up prices for dozens of major artists. At the same time, the art world is as inundated with forgeries as ever. The two are of course inextricably linked, and the digital age is adding extra layers of complexity to the picture.

Karen Sanig, head of Art Law at Mishcon de Reya, opened a Mishcon panel discussion on ensuring authenticity in the digital age with a sobering statistic: "With 6% of the $45 billion fine art market now trading online, buyers are acquiring art without proper checks," she said. "This is scary. People are buying art, not on the basis of expertise, but from an image on the internet, Instagram or WhatsApp."

Establishing the authenticity of a work of art has never been straightforward. Traditionally, galleries and collectors have relied on the advice of scholars and the provenance, or documented ownership historyof an artwork to determine whether it is genuine, but neither of these is infallible. Experts make mistakes; and provenance can be faked.

Meanwhile, the digital world has only exacerbated these problems.

Some recent forgeries have been so good they have taken in the entire art establishment.

In 2011, Knoedler & Co, one of the oldest galleries in North America, was forced to close its doors after a scandal, involving alleged works by Abstract Expressionists, including Willem de Kooning and Mark Rothko. The forgeries were good enough to fool Domenico de Sole, chairman of Sotheby's, into buying one of the faux Rothkos. When the deception was uncovered, Knoedler's faced an avalanche of lawsuits.

Over the years, Knoedler is alleged to have sold more than 60 forgeries (lawsuits remain pending). "There could not have been 63 works of Pollock, Rothko and others that had gone under the radar," says David Anfam, a Rothko expert and author of the definitive catalogue raisonné of the artist. "Had this been known, the game would have been up." Knoedler told prospective buyers that Dr Anfam had "seen" the Rothkos for sale, implying that he had authenticated them. Dr Anfam explains: "I never saw the original painting, just an 8x10 transparency. If anyone tries to sell you a painting saying it has been 'seen' by so-and-so, or that it will be included in the next catalogue raisonné, alarm bells should go off."

On the other side of the Atlantic, European galleries and auction houses, including Christie's and Lempertz, were duped by the forger Wolfgang Beltracchi, who churned out exquisite copies of German Expressionists such as Max Ernst and Fernand Léger over decades.

Beltracchi was exposed when one of the forgeries, "Red Picture with Horses", purportedly by Heinrich Campendonk, ended up in Dr Nicholas Eastaugh's lab in London. Its owner, a Maltese investment company, had become suspicious. Dr Eastaugh, an expert on the history of art materials and pigments, detected titanium white – manufactured since the 1910s, but not available to artists until decades later. The anachronism landed Beltracchi in jail. Freed in 2015, he now holds exhibitions of his own "genuine fakes".

"This is a pattern that we see in many emerging art markets," Dr Eastaugh said. "The newly wealthy want to buy their cultural heritage. Soon after, forgers see the opportunity to make money by producing fakes. In India, Pakistan and Iran, prices are rising on the back of aggressive buying. These are also places where scholarship about specific artists is weak, which makes it easier for the fraudsters to fudge provenance."

On the internet, nobody knows you are a fake

The internet has  provided a bounty for fraudsters. Genuine online catalogues have been tampered with to insert pictures of fake works, bestowing credibility by association. Not only fake works, but fake artists with fabricated careers have been invented to feed a hungry art market.

On the internet, you can find paintings for sale by Anna Kagan, an alleged member of the early 20th century Russian Avant-Garde. Online histories claim she worked and exhibited alongside Russian greats, such as Kazimir Malevich and Natalia Goncharova. But according to Christina Lodder, Honorary Professor of the History of Art at Kent University and an expert on Russian modernism, Anna Kagan is a fabrication. Her name is similar enough to be confused with Nina Kogan, a bona-fide member of the Russian modernists, "but no work on Anna Kagan has ever been published in Russia, and there are no paintings of hers in Russian museums."

"Unscrupulous dealers are making money not only by selling fake works, but fake artists and fake careers to go with it," Professor Lodder says.

In this respect, art is no different from other parts of the online world, where fake news is manufactured to sway elections, and falsehoods are amplified by social media to destroy – or build – reputations. Establishing authenticity in this context requires tracking down the originator of the online information about an artwork. Digital sleuthing is becoming part of the arsenal for detecting fraudsters.

Will robots replace the knowledge of experts?

In response to the spread of online art fraud, scientists and IT specialists have developed new methods to protect genuine works of art. Electronic tagging – using bits of unique lab-produced DNA to label works of art – is now available. Blockchain – the electronic ledger invented to store crypto currencies – is being considered as a secure vehicle in which to store information about a work of art: its ownership, provenance and history, as well as the reports of experts and any other related content.

In addition, forensic art science has evolved from the analysis of pigments and materials. Dr Eastaugh says he is working more closely with art historians to develop a deeper understanding of what makes an artist's style unique. 3D surface scans can reveal how an artist applied paint on canvas; machine learning can help codify patterns in working practices and the choice of techniques.

Working with the Josef Albers Foundation, Dr Eastaugh and his team identified 50 technical features that should be in an Albers painting, for example. This may be as close as science can get to "defining" the essence of an artist's style – knowledge that lay previously in the realm of art scholarship.

And while these techniques may not be foolproof, experts agree that the future of authentication lies in the collaboration of art historians, scientists and technologists. All are needed to develop a deeper understanding of artists and the body of their work. The digital age has thrown up an issue for the art world that mirrors other spheres too: never has the need to distinguish the real from fake been greater.

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