BY THE TIME the final chunk of the Cartier jewelry empire was sold off in the 1970s, its founding family was almost entirely dispersed and disinterested.

Almost everyone was wealthy — the Cartier family had an uncanny knack for marrying into money, then making even more of it. And even though four generations of Cartier men had worked tirelessly to create a business that elevated jewelry salesmanship from “mere trade” to an art form, their descendants were more interested in bobsledding in St. Moritz than hawking the company’s famous Tank watches.

This rise and then — instead of a “fall,” let’s call it a “plateau” — is artfully documented in a new book, The Cartiers, by a member of the family’s sixth generation, Francesca Cartier Brickell.

Several years ago, Brickell discovered a trunk full of family correspondence in her grandfather’s wine cellar and used it as a starting point to chronicle her illustrious family.

What saves the book from being yet another variation on the “from shirtsleeves to shirtsleeves in three generations” parable is that the family business hinged on the shifting fortunes of the world’s super rich. As a result, the story of the Cartier family is the story of wealth creation in the 19th and 20th centuries as it moved in waves from country to country.

Massive wealth, at least from the Cartiers’ perspective, was often a zero-sum game: The Russians bought until the Bolsheviks came to power, at which point the Americans stepped in. After the Depression hit, the Americans bowed out, at least for a time, to be replaced by celebrities and petroleum-rich Middle Easterners.

Cartier managed to benefit from both the rises and the falls. The company would sell jewels at retail prices to its rich clients, then buy them back wholesale (or sell them on commission) once those same clients fell on hard times. “The same grand duchesses who had been snapping up diamond tiaras and sapphire stomachers before the war,” Brickell writes, “were now selling them back, often gemstone by gemstone, just to survive.”

The Cartier dynasty was founded in the late 1840s by Louis-Francois Cartier. His little Parisian shop, where he sold mostly knickknacks, took off only when he began to enjoy the patronage of Princess Mathilde Bonaparte, the niece of Napoleon I.

Initially, she asked him to repair a necklace, but she soon became a bona fide customer, purchasing more than 200 items. And even though Cartier’s first client base was wiped away after Napoleon III abdicated following the Franco-Prussian war, the company continued to expand thanks to Louis-Francois’s son, Alfred, who married an heiress to a manufacturing fortune.

Alfred first worked in London after the Franco-Prussian war “as a middleman between fellow French exiles forced to sell their gems to pay for their new lives, and the English aristocracy whose daily rituals demanded a change of jewels for every meal,” Brickell writes. After moving back to Paris, he expanded until the company counted multiple princes and princesses among its clientele.

Even though Cartier was selling significant jewels to significant people (it made the wedding jewels for Princess Marie Bonaparte’s marriage to Prince George of Greece in 1907), it was still a distant second or third to such companies as Boucheron, Fabergé, and even Tiffany. It was only the next generation of Cartier children — Louis, who first married a French heiress, and then a Hungarian heiress; Pierre, who married an American heiress; and Jacques, who did the same — who elevated Cartier to a global powerhouse.

Using the Rothschilds as a template, the three brothers agreed to open outposts in separate world financial centers. Louis, the oldest, opened in Paris; Pierre, the middle son, in New York; and Jacques, the youngest, in London.

Louis helped develop the famously playful aesthetic known as the “Cartier style” and, most important, broke into the Russian market.

His entree was via Grand Duchess Vladimir, a jewel-obsessed sister-in-law of the czar of Russia. Not only did she buy a six-strand pearl necklace interspersed with diamond eagles, Brickell writes, but she opened doors for the Cartier family, making introductions to other members of the Russian imperial family and facilitating sales.

Meanwhile, Pierre first set up the London office (Jacques would later take it over) and then moved to New York, where he began to cultivate the country’s nouveau riche. He sold the Hope Diamond to Evalyn Walsh McLean for $180,000 (about $4 million today), and exchanged a $1 million pearl necklace for Cartier’s Fifth Avenue flagship mansion, which it still owns today.

Jacques, something of a late bloomer, traveled first to India to build relationships with the country’s fabulously rich Maharajas, and then took over the London branch, creating jewels for the royal family and English aristocracy. Queen Elizabeth II, for instance, eventually tasked Cartier with turning a 23.6-carat pink diamond into a brooch.

Even as the brothers were expanding their client list, that clientele was changing dramatically. The first blow was the Russian revolution. Grand Duchess Vladimir escaped Russia and had one of her friends sneak out several suitcases filled with jewels from her St. Petersburg palace. Prince Yusupov, another Cartier client and one of the richest men in the world, also escaped the Bolsheviks with many of his jewels intact, and, like the grand duchess, began to discreetly sell them through the Cartiers.

The family’s commitment to discretion, combined with their rolodex, made them the perfect intermediaries. “The Cartiers were privy to levels of trust from the Romanovs that would have been impossible to reach had they not visited their family homes prior to the revolution,” Brickell writes. “As a result, they were often the first to learn when exiled Russians were keen to sell their imperial jewelry, a key advantage when competing with their professional peers.”

The same thing would happen to the Maharajas, whose fortunes were obliterated by land reforms and new taxation structures in the 1970s.

Suddenly, Arab sheikhs and American movie stars like Liz Taylor were the clients spending the big money. But by that time, all three brothers were dead, and their children, with the exception of Jacques’s son Jean-Jacques, were part of the jet set themselves.

Because The Cartiers is the story of the family rather than the company, it begins to peter out well before Cartier’s eventual sale in 1974. (Today the company is owned by luxury goods conglomerate Richemont.)

Brickell, the granddaughter of Jean-Jacques, has no discernible nostalgia for the lost business, and as a result the book’s real value comes as a chronicle of the global vicissitudes of extreme wealth.

In 1958, for instance, King Faisal II of Iraq informed the family that his fiancee’s bridal registry would be at Cartier. A few weeks later, he and his family were murdered in a coup. “As with the Bourbons and the Romanovs,” Brickell writes, “the flip side to great wealth and power was inequality and, with it, social instability.” — Bloomberg