The world’s most expensive painting, the “Salvator Mundi,” purportedly by Leonardo da Vinci, was supposed to go on display next week in the world’s most famous museum, the Louvre, in a blockbuster exhibition marking the 500th anniversary of Leonardo’s death. Barring a last-minute surprise, however, the painting will be a no-show.

The “Salvator Mundi” sold for a record-shattering $450.3 million in 2017. But in the two years since the sale at Christie’s, controversy over the painting’s attribution has intensified.

The Louvre has long said it wanted the “Salvator Mundi” in its show. The exhibition’s curators, Vincent Delieuvin and Louis Frank, explicitly requested it from the owner, believed to be Crown Prince Mohammed bin Salman (the same Saudi ruler whom the CIA has accused of ordering the assassination of Washington Post columnist Jamal Khashoggi).

The opening of “Leonardo da Vinci” is just days away, but, according to museum spokeswoman Céline Dauvergne, “we are still waiting for an answer.”

The silence is excruciating, and hard to fathom. But it may be that the owner is worried about the consequences of lending the work, and awaiting assurances the Louvre is refusing to give.

The issue is this: Some experts are convinced that Leonardo painted the “Salvator Mundi” (the vast majority of it, anyway) and have staked their reputations on it. Others are unconvinced, believing that the painting, which was in a terrible state and needed years of restoration and repainting to make it presentable, was probably painted more by the master’s assistants or pupils.

If the “Salvator Mundi” were displayed in the Louvre’s exhibition as an autograph Leonardo, it would gain the prestige of being rubber-stamped by the highest institutional authority in the world: the museum that owns the Mona Lisa, as well as four other undisputed Leonardo paintings (more than any museum).

But the Louvre curators, who plan to display works “from the master’s circle” in the exhibition beside autograph Leonardos, have reserved the right to label the “Salvator Mundi” as they see fit.

“If it comes,” Delieuvin said in a Sept. 9 interview in the French newspaper Le Figaro, “we will say what we think. Whether it really is by the hand of Leonardo, partly so or not at all.”

The potential repercussions of the Louvre “saying what it thinks” are enormous. The differences between displaying the “Salvator Mundi” as, on the one hand, “by Leonardo da Vinci” and, on the other, “by Leonardo and workshop,” or some similar formulation are massive. A slight shift in phrasing could potentially lower the valuation of the painting by hundreds of millions of dollars.

Bin Salman, if he is the owner, may not be willing to expose his acquisition to that risk. In which case, the “Salvator Mundi” will probably remain in hiding, possibly on the Saudi ruler’s superyacht, the Serene, as one rumor claimed; more likely in a vault in Switzerland.

The world had a new Leonardo

It remains unclear why a $450 million painting that is the subject of such intense global interest vanished, so that not even an institution with the clout of the Louvre can get an answer as to its availability. But the story of how the image of Jesus as savior of the world came to be so valued is easier to tell. And it’s not entirely edifying.

Just 12 years before the “Salvator Mundi” sold at Christie’s for almost half a billion dollars, art dealers Robert Simon and Alex Parish purchased it at an estate sale in New Orleans. The purchase price? Only $1,175. (According to Ben Lewis, the author of “The Last Leonardo: The Secret Lives of the World’s Most Expensive Painting,” “no object, item or substance in the known universe has ever risen in value so fast and by so much.”)

The crucial turning point in the “Salvator Mundi’s” astonishing rise in value was a decision by another prestigious museum, London’s National Gallery of Art, to include it as an autograph work by the master in a Leonardo exhibition in 2011.

Until then, the painting had been shown around, and even offered for sale, but experts had been reluctant to accept the attribution. The National Gallery show marked the arrival of a new Leonardo in the world — the first one to gain widespread acceptance in 100 years.

And it made the painting suddenly very marketable.

But on what basis had the curator of that show, Luke Syson, included it?

Syson studied the painting and its provenance very closely. “The technical information is important,” he told Lewis. “But the sense of how a painting communicates is just as important.” The “Salvator Mundi,” he said, “seemed to hover somewhere between our realm and something spiritual.”

Of course, Syson knew that a painting must do more than merely “hover between realms” to gain acceptance as an autograph work by Leonardo. So back in 2008, he asked the painting’s owner, Robert Simon, to bring it across the Atlantic to the National Gallery to be examined by five great Leonardo experts.

Two of the invited experts came from Milan, one from New York, one from Washington and one, Martin Kemp, from Oxford.

None were asked to authenticate the painting. The discussion in the National Gallery’s conservation studio was informal, and no notes were taken. But after the meeting, Syson told Nicholas Penny, who was then the director of the National Gallery but did not attend the meeting, that “the experts had agreed that the painting was indeed by Leonardo himself.”

It was on this basis that the “Salvator Mundi” was included in the National Gallery show.

Yet Lewis has since revealed that the five experts were not, in fact, in agreement. The two Italians, in particular, were surprised to see that, three years later, their comments had been interpreted as a “thumbs up.” They had not offered a settled opinion and appeared to harbor doubts. Carmen Bambach — a curator at the Metropolitan Museum of Art in New York and the author of a new four-volume study on Leonardo — was especially skeptical.

But the imprimatur the painting gained from Syson’s characterization of the meeting and its subsequent inclusion in the National Gallery exhibition changed everything. The world had a new Leonardo.

Just two years after the National Gallery exhibition, Parish and Simon sold the “Salvator Mundi” to a man named Yves Bouvier for between $75 million and $80 million. Within days, Bouvier had flipped it to Russian billionaire Dmitry Rybolovlev for $127.5 million. (When Rybolovlev discovered this, he was outraged and sued Bouvier. The case is ongoing.)

Four years later, Rybolovlev (who in 2008 had bought a villa in Palm Beach, Fla., from Donald Trump) put the “Salvator Mundi” up for sale again. The bidding at Christie’s started at $70 million. At about $90 million, it seemed to be in danger of petering out.

But it soon clicked back into gear and before long surpassed the record for a painting sold at auction — $179 million for Picasso’s “Les Femmes d’Algers (Version ‘O’).” It continued upward from there.

Kemp was watching the proceedings online. He thought the painting would struggle to fetch more than $110 million.

“So I went to bed,” he told the Art Newspaper. “At 2 o’clock in the morning my phone started ringing and I opened my emails and they were all going bing bing bing and all hell broke loose. . . . It was completely crazy.”

Asked for his take on the record-smashing price, Kemp said: “What it shows is that Leonardo . . . is of a different league. . . . So I don’t think this is a world record price for a painting in the normal market. It’s a world record price for a Leonardo, which is a completely separate thing from anything else. It’s just astonishing.”

He is right. It’s a story as incredible as the art world has ever seen.

But even as they present themselves as spectators, experts like Kemp and Syson must also be conscious of the outsize role they have played in the valuation of the “Salvator Mundi.”

“We’re all bombarded,” Syson told Lewis, “by hopeful petitioners saying, ‘I’ve found a Leonardo and no one believes it, but you will when you see it.’ It’s usually a hideous, ghastly, sad thing.” Kemp, as one of the world’s leading experts, has been even more bombarded by requests to examine dubious pretenders.

The “Salvator Mundi” is clearly in a different category. It’s a compelling case, and it may indeed be “the real thing.” But the question of whether it is actually by Leonardo is exceedingly complex, and there remain as many reasons to question the attribution as to accept it.

In this 500th anniversary year, there is intense competition among museums to borrow works by Leonardo. Worldwide, there are only 13 to 15 paintings by the master, and even the Louvre has been struggling to borrow the works it would like. Last week an Italian court blocked its request to borrow Leonardo’s most famous sketch, the so-called “Vitruvian Man.”

Not getting the “Salvator Mundi” would be a further blow. But given the stakes, and the events set in motion by London’s National Gallery back in 2011, who can blame the Louvre for holding its cards close and exercising a little caution?