Fake or Mona Lisa? Tips for spotting a real painting

(Left) The Mona Lisa by Leonardo da Vinci; (Right) The contentious “Isleworth Mona Lisa”
(Left) The Mona Lisa by Leonardo da Vinci; (Right) The contentious “Isleworth Mona Lisa” - Universal History Archive/UIG via Getty Images/ Alamy

In art, truth lies in the eye of the beholder. Except, of course, it doesn’t.

For centuries, the sole method of telling whether a work of art was real or fake was that of a curator’s judgement. This encounter – one person, in front of a canvas, forming an opinion – was all we had to go on. Now, X-ray, forensic pigment analysis, catalogue histories and provenance enquiries can all be brought to bear.

Yet to a remarkable extent, the question of authenticity is still largely decided by that old-fashioned method – an expert, poring over a painting, then straightening up, clearing their throat. And trying to upend art history.

Case in point is the recent display of a “second” Mona Lisa. The “Isleworth Mona Lisa” – named after the location where it was bought by a dealer in 1913 – shows a similar-looking woman to that of Leonardo da Vinci’s landmark 1518 portrait of Lisa del Giocondo, now in the Louvre. Yet the Isleworth Mona Lisa features a different background with pillars, and its subject is noticeably younger.

No matter, says the Zurich-based Mona Lisa foundation, who are promoting the artwork on behalf of its Swiss owners. Their Mona Lisa is of the same woman – but made about a decade before the Louvre painting. In fact, they claim, the Isleworth is the true artwork painted from life: the Louvre version is an imagined projection, showing her ten years older. The Mona Lisa Foundation has staked their claim by exhibiting the painting in Turin.

The "Isleworth Mona Lisa"
The "Isleworth Mona Lisa" - Alamy

The Italian arts ministry is less than thrilled. “It’s junk, a wind-up, it lacks the soul of Leonardo and I don’t know why anyone believes it,” fumed Vittorio Sgarbi, their junior arts minister.

Yet how would one go about authenticating the Isleworth Mona Lisa? These are the elements an art historian would look out for.


Ideally, says Philip Mould, art dealer and expert on Fake or Fortune?, the BBC’s hit series that authenticates works of art (or figures out they’re a fraud), “you’d want to track the history of an artwork back to the moment it left the artist’s easel”. In Britain, this analysis of a painting’s movements and its owners is referred to as its provenance – and it can often make a compelling case for its authenticity.

“It’s the sort of evidence a jury understands,” explains Mould. “If you can work out where that artwork has been since the paint was wet, that’s a very powerful way of proving whether it’s legitimate.”

But he warns: “Fakers sometimes piggyback on the provenance of an artist, such as by claiming it was made in their studio at the same time as other notable works. Something similar happened when Leonardo’s Salvator Mundi was first exhibited. It was meant to have been in the collection of Charles I, but that was subsequently disproved. That doesn’t mean it was fake, but it shows the difficulty with provenance. You have to question the written assertions about an artwork’s history as much as the physical artefact.”

Philip Mould, art dealer and expert on Fake or Fortune?
Philip Mould, art dealer and expert on Fake or Fortune? - Clara Molden

Stylistic analysis

The next stage in authentication is to examine the artwork in light of other, authenticated pieces by the same artist. How much does it replicate their stylistic tics? Could it conceivably be by the same hand?

In the case of an artist such as Leonardo Da Vinci – of whom only 15 authenticated artworks survive – this process is particularly crucial and fraught. “With artists who are technically really accomplished, there’s often almost a codified way in which they paint,” says Mould. “Of course, it does vary between earlier and more mature works. But an artist’s style is analogous to handwriting – to know it, is to know them.”

Among the tell-tale marks are the modulation of shadows and colour; the movement of the brushstrokes on the canvas; and the way they model their subjects. Leonardo Da Vinci, for instance, is famous for his exquisite deployment of sfumato – the delicate, luminous way colours and edges shade into one another. “His borders almost dissolve before your eyes,” points out Mould. “They come out the ether at you.”

Leonardo da Vinci's masterpiece: the Mona Lisa at the Louvre Museum in Paris
Leonardo da Vinci's masterpiece: the Mona Lisa at the Louvre Museum in Paris - ERIC FEFERBERG/AFP via Getty Images

Historians will also consider the characterisation of an artwork: does it reflect the intangible way an artist usually considers a subject? Mould says: “From the cradle to the grave, we’re taught to read faces. So when we consider portraiture, the appreciation goes beyond technical style – it’s about familiarity with the way the artist paints people. Does this artwork seem to contain the particular response to humanity you associate with the artist?”

Lastly, they consider the artwork’s pentimenti. This Italian term roughly translates as “regrets” and they are a record of the artist’s mistakes, changes of mind and roads not taken. Typically, these are manifested, especially in Old Masters, in raised, lumpy patches of paintwork where an artist has gone over and over a particular problem: the creative act, fixed in pigment, centuries after the artist died. The Salvator Mundi, for example, shows Leonardo Da Vinci worrying away at Jesus’s pinched hands, trying to capture their exact, beatific stillness.

Salvator Mundi attributed to Leonardo da Vinci
Salvator Mundi attributed to Leonardo da Vinci - VCG Wilson/Corbis via Getty Images

Scientific analysis

An art historian’s toolbox, though, is not only reliant on subjective response. On the contrary, any major contested artwork is put through a rigorous array of tests which, while not infallible, can nonetheless bolster an authenticity case.

Often, a tiny sample of paintwork is taken and analysed for its constituent parts. This process determines whether the artist used similar paints in their other authenticated compositions. But it also reveals something equally significant – whether the painter could have employed those materials at all.

Forgers are sometimes caught short because they use a colour which was invented after the artist’s death; this was the case with a ‘Constable’ which, it transpired, had been painted by his son. The giveaway was a signature in the corner which gave the date as “184-”. Constable, who died in 1837, would therefore have had a hard time finishing it.

X-ray and infrared scanning also help fix authenticity. In a similar way to the pentimenti, this analysis can reveal an artist’s workings, whether they changed their mind halfway through composition – or even began a whole new painting on top of an old, abandoned one. For some artists, such as Holbein, these techniques are especially useful, says Mould. “We can see the underlying drawing lines, which is very helpful as we have other, existing examples of [Holbein’s] sketches to compare them to. It’s another graphic manifestation of the artist’s signature.”

Holbein's preparatory sketches on display at The Queen's Gallery, Buckingham Palace
Holbein's preparatory sketches on display at The Queen's Gallery, Buckingham Palace - Jonathan Brady/PA Wire

Who is the messenger?

Despite the high-tech tools available, historians rely on hunches as much as anyone, Mould argues. “It’s ridiculously subjective, but the next stage is where human intuition comes in: who is making these claims of authenticity – and do they have a stake in lying?

“I don’t want to make any claims about the two Mona Lisa paintings, but I sometimes find it useful getting an insight into whoever is presenting the picture and what is motivating them.” Like Poirot, a successful art authenticator learns to trust their guts.

Subject matter

“In my experience, fakers go one of two ways,” notes Mould. “They either reach for the cliché – or they are a bit subtler and produce something which could plausibly be a minor, less well-known work. There’s clearly more of an incentive to produce something that everyone wants… and in the case of the Mona Lisas, you can draw your own conclusions.

“But they might try the opposite and produce something which requires a bit of a leap of faith, such as a work of juvenilia. For instance, I’ve found forgeries among the work of well-known 20th Century artists by looking closely at pictures of their studios and you’ll spot a work from 20 years earlier. And the forger has clearly seen the same photo and tried to replicate that earlier, less notable painting.”

Philip Mould alongside an early portrait of Queen Elizabeth I hung at Philip Mould & Co gallery, Pall Mall
Philip Mould alongside an early portrait of Queen Elizabeth I hung at Philip Mould & Co gallery, Pall Mall - JULIAN SIMMONDS

Age matters in other ways, too. Some forgers will go as far as purchasing canvases from the same time period, sometimes even painting over other artworks, so that the art looks older enough. The most successful try to disguise their fraud by using period-appropriate paints, too.

But Mould cautions: “Making a painting look convincingly old is one of the toughest jobs for a forger. It can look really clumsy, but even if it’s more effectively done, an experienced curator might be able to spot it. It’s not one thing in particular – more of a general feeling that the artwork can’t be that old.”


In the art world, reputation is all. To a large extent, the authenticity of an artwork rests on the endorsements of scholars – sometimes, even with the most famous, there will only be a handful of these trusted brahmins.

“These people establish their status in various ways,” explains Mould. “Perhaps the most powerful is whether they have written the catalogue raisonné, which itemises every artwork the artist is known to have made and is effectively the Bible of a particular artist. They can also be people involved in the museum sector or the commercial art market. And most artists have an established committee whose judgement is respected. Again, it’s like a court case: think of these scholars as expert witnesses. And by and large, the art world listens to them.”

As it stands, the Isleworth Mona Lisa has yet to be publicly subjected to these tests. Still, Mould sounds a final note of caution for those claiming it as authentic – or not. After all, judging authenticity is a devilishly tricky, all-too-fallible task.

“Ultimately, authentication is a human emotional response – and like all human responses, there’s an element of subjectivity. It’s never as cut and dry as one would hope,” he concludes with a smile.

Philip Mould owns the gallery Philip Mould & Company and is a presenter on Fake or Fortune?, available to watch on BBC iPlayer