Leonardo DiCaprio wears a Prop Art Deco Rectangular

In the summer of 1922, on a rainy afternoon in Nick Carraway's small rented cottage on Long Island, Jay Gatsby stands in front of Daisy Buchanan for the first time in five years. He has filled the room with flowers and arrived in an ivory linen suit far too fine for the modest surroundings. He is so nervous that when he leans his head back against the mantel he knocks a small clock off its perch, then catches it with trembling fingers before it can hit the floor. In Fitzgerald's novel that clock has stopped at ten minutes to two. Gatsby has built a fortune to win Daisy back and to repeat a summer that is already five years gone, and the first thing he touches in front of her is a clock that no longer runs.

Time is the obsession at the center of this story, and it was an obsession of the man who wrote it. Fitzgerald threaded clocks and watches through all of his early books. His wedding gift to Zelda was a jeweled Cartier wristwatch, and by his own account he once sat down in New Orleans and wrote a short story in a single day for the express purpose of buying a platinum and diamond wristwatch that cost six hundred dollars. So it is fitting that Baz Luhrmann's 2013 film, which won Academy Awards for its production design and its costumes, lavishes the same attention on its jewelry. Tiffany and Co. dressed the production and made bespoke pieces for the cast, including a set of gold cuff links for Gatsby himself.

Which is what makes the watch on Leonardo DiCaprio's wrist so strange. You can see it in the reunion scene, a slim rectangular steel piece with a white dial on a folding-clasp bracelet, exactly the kind of art deco rectangle every jeweler was turning out in the 1920s. For years the internet settled on a confident answer: it had to be a Jaeger-LeCoultre Reverso, the famous flip-case watch with the same clean rectangular lines. There is one problem. The Reverso was not patented until March of 1931, designed so that polo players in India could swivel the dial to the underside of the wrist and shield it from a stray ball. Gatsby's story takes place nine years before that watch existed. The most popular answer is a watch from a future Gatsby never reached.

So what is it? The people who have looked hardest do not agree. Revolution, surveying the watches of the Gatsby films for the novel's hundredth anniversary, writes that close inspection shows the piece to be one of Tiffany's own in-house creations rather than a Reverso. The costume researchers at BAMF Style land somewhere humbler: the watch was most likely made just for DiCaprio, and beyond that the details remain a mystery. No press release ever named it. No brand has ever claimed it. The reunion at the heart of the film turns on a stopped clock, the novel behind it cannot stop thinking about watches, and yet the one on Gatsby's own wrist is the timepiece no one has ever been able to identify.