As De Beers aggressively marketed diamonds as symbols of romance and adventure, the cartel found an early ally in Hollywood. The promise of the diamond came to full fruition on the silver screen, where luminescence enticed the sparkling gem.

In the late 1930s, De Beers hired the N.W. Ayer advertising agency to boost diamonds' appeal among American consumers. It was not an opportune moment, as a worldwide depression starkly reduced demand for luxury goods, including diamonds.

According to writer Edward Jay Epstein, author of The Rise and Fall of the Diamond, the N.W. Ayer plan to romanticize diamonds required subtly altering the public's notion of how a man should court a woman. So, the advertising agency proposed to De Beers that they exploit the relatively new medium of motion pictures. "Motion pictures seldom include scenes showing the selection or purchase of an engagement ring to a girl," stated an Ayer memo to De Beers, cited by Epstein. "It would be our plan to contact scenario writers and directors and arrange for such scenes in suitable productions." The Ayer plan also included giving diamonds to public personalities, such as film stars and even the British royal family. The gems would offer symbols of indestructible love, according to Epstein.

In a 1940 report to De Beers cited by Epstein, Ayer reported, "A long series of conferences with Paramount officials, capped by your own efforts, succeeded in changing the title (of a film) from 'Diamonds are Dangerous' to 'Adventures in Diamonds.'" The memo detailed other ways the company had changed scenes to boost prominence for diamonds. Epstein writes that the Ayer memo reasoned that Americans "have not been conditioned by their environment to diamond purchases. Aside from the engagement rings, they have no diamond tradition. But they are going to be influenced by…what they see their favorite starts wear."

Maura Spiegel, professor of literature and film at Columbia University, says Hollywood successfully linked luxury, romance and female power with demand for diamonds.

"Diamonds had a special value, in part because if you wanted a piece of the glamour that you saw in the movies, you couldn't buy a miniature mink coat or a piece of a Rolls Royce, but you could buy a little tiny diamond or a ring with diamond chips in it, and you had the real thing," Spiegel says.

As the diamond campaign was gathering pace, Harry Winston, one of America's leading jewelers, set up shop in Hollywood to follow De Beers dictum: boost the diamond's star appeal…and boost sales.

According to Maura Spiegel, Winston stood out from a number of prominent jewelers of the period.

"He's had the longest staying power. He was there, loaning diamonds to the stars for every major public event. Harry Winston really understood the construction of an image, which of course Hollywood also understood. He never allowed himself to be photographed—he said it was for security reasons, but it certainly increased the mystique.

"He promoted the status of diamonds through his famous gesture…he donated the Hope Diamond to the Smithsonian, thereby making it the property of the American people. In some sense, he both elevated the status of the diamond by making it an object worthy of the Smithsonian museum and at the same time makes this sort of democratizing gesture," says Spiegel. She notes that to this day, the hall of gems which houses the Hope Diamond is the Smithsonian's most popular exhibit.

This marketing scheme continues today. The House of Harry Winston doles out millions of dollars in diamond jewelry—on loan of course—to Hollywood's biggest stars for the Oscars. In 1999, the company outfitted Whoopi Goldberg with more than 40 million dollars in diamond jewelry. Early Hollywood films helped establish the ritual of a man surprising a woman with a piece of diamond jewelry.

"One of the arguments for why the movie scene is invariably a surprise gift of a diamond, is because there was some feeling that they wanted to train men to buy it as a surprise for fear that a woman might choose a dishwasher instead, or some other practical item," says Spiegel.

But diamonds also played on complex sexual politics. In the film "Gentlemen Prefer Blondes", Spiegel says diamonds represented not just love but other enticements. "The diamonds cast a spell on Marilyn Monroe in that film. It's as if she's hypnotized. She's completely entranced by the mystique but she's also a completely practical girl and she understands that you need something you can count on. Men are not trustworthy, they take and they go. So you need to make sure you get something that you can hold on to, like diamonds. They will not change because they're forever."