The most famous watchmaker in the world belongs to a family of dial makers. That sentence sounds wrong the first time you read it. It is the plain truth, and the story behind it is one of the best in watchmaking.

Patek Philippe is the house of perpetual calendars and minute repeaters, of movements finished to a standard nobody has matched for a century. Yet the family that has owned it since 1932 did not come from movements. They came from the face of the watch. For thirty years before they bought Patek Philippe, the Sterns made its dials. And for eighty years after, a separate branch of the same family business quietly made dials for nearly everyone else: Rolex, Vacheron Constantin, Audemars Piguet, Cartier. If you collect vintage watches, there is a fair chance you have owned a Stern dial without knowing it. We can prove it. One of ours is signed.

In 1898, Henri and Louise Stern opened a dial-making atelier in Geneva. A husband and wife, a workshop, and one specialism: enamel dials, usually white, fired again and again at temperatures between 700 and 900 degrees until the surface came out of the kiln flawless. From 1903 their sons traded as Stern Frères, the name the watch world would know for the next century.

To understand why a dial house could matter so much, remember how Swiss watchmaking actually worked. The great names did not make everything themselves. The industry ran on networks of independent specialists, each supreme at one thing: cases here, hands there, dials somewhere else, and the brand at the centre assembling, adjusting and signing the finished watch. The system rewarded depth. A workshop that did nothing but dials, decade after decade, became very good at dials.

Stern Frères became the best known of them all. In 1906 the workshop moved to the Place des Volontaires, on the banks of the Rhône, where water power drove its polishing wheels. In 1927 the family built a modern factory at La Jonction, its façade over the river. By the 1920s its clients included nearly every great Geneva house, and one above all: Patek Philippe, then still owned by bankers and shareholders, bought its dials from Stern Frères.

The Great Depression reached Geneva slowly and then all at once. Patek, Philippe & Cie had spent the 1920s building watches for American millionaires. By the early 1930s the millionaires had stopped buying, and the company, for all its patents and prize medals, was looking for a solvent buyer for a majority of its shares.

It did not have to look far. Charles and Jean Stern, the brothers then running the family dial business, knew Patek Philippe from the inside. They had supplied its dials for years. They understood what the firm was worth beyond its balance sheet, and what Geneva would lose if it failed or fell into careless hands. In 1932 they bought a controlling interest, and full ownership followed soon after.

It is worth pausing on how unusual this was. Suppliers do not, as a rule, rescue their clients. A dial workshop buying the most prestigious watchmaker in Switzerland was roughly the equivalent of a printer buying a great publishing house. But the Sterns were not speculators picking over a distressed asset. They put a watchmaker, Jean Pfister, in charge, and under him Patek Philippe stopped buying in movement blanks and began making its own. The first fully in-house calibre, the 12'''120, arrived in 1934. Independence became the house doctrine, and it has never been abandoned since.

The same year the Sterns took over, the company launched a plain round wristwatch, 31 millimetres across, with a flat bezel and applied hour markers. It was the first Patek Philippe to carry a reference number: the reference 96, founding model of the Calatrava line, named for the cross the firm had registered as its trademark in 1887. Who drew it is not recorded. What can be said is that the reference 96 is, above all, a triumph of dial design: everything the watch has to say, it says on its face. It is exactly the watch a family of dial makers would make, and it stayed in production for over forty years.

Here is the part of the story that usually gets lost. Buying Patek Philippe did not end the dial business. Stern Frères carried on as an independent supplier, and for the next half century it remained the most famous dial maker in Switzerland. Rolex and Vacheron Constantin went on buying their dials from the family that owned their fiercest competitor, for decades, because nobody else could do the work at that level.

Its finest era was the enamel age. From 1940 to 1960 Stern produced cloisonné and champlevé enamel dials that now rank among the most valuable objects in collecting: miniature seascapes and maps in glass, built from gold wire and fired colour. The celebrated Geneva enameller Marguerite Koch designed dials commissioned through Stern for Rolex, Vacheron Constantin and Patek Philippe. On the back of one of them, a caravel in full sail made for Rolex in 1953, the order books record the stamp you decoded above.

In 1944 Charles Stern died, and the dynasty divided its inheritance. His son Henri ran Patek Philippe, building its American business through the Henri Stern Watch Agency in New York. Another son, Charles, took the dial house with his uncle Marcel, and ran it for three decades while sailing for Switzerland at two Olympic Games and twice winning the Bol d'Or on Lake Geneva. One family, two houses: one made the watches, the other made the faces of everyone else's.

The dial house had its own dramas. The quartz crisis of the 1970s cut its workforce down severely. Then, at the end of that decade, Cartier arrived with an order that changed everything: 150,000 dials for the new Must de Cartier, roughly ten times the firm's entire annual capacity. Stern said yes, built a new factory across the French border to cope, and carried itself through the leanest years the Swiss industry has ever known.

The two halves of the story end very differently. In 1996 the dial business, by then trading as Stern Créations, was sold out of the family to Orior Holding for an estimated 45 to 47 million Swiss francs, with 260 employees. In 2000 it passed to the Richemont group. Many clients quietly ended their agreements rather than share trade secrets with a conglomerate that owned their competitors. Rolex, to its credit, kept ordering for another ten years. Richemont renamed the firm Manufacture Stern 1898, merged it, and wound it down. In June 2016, after 118 years, the dial house closed. Its last mention in the state registers passed virtually unnoticed. The order books and design archive survive in private hands, and the finest reference on the company, Dr Helmut Crott's The Dial, was written from them.

The watch company the dial makers rescued took the opposite path. When quartz nearly ended mechanical watchmaking in the 1970s, Henri's son Philippe Stern held the line: he kept the tooling, kept his watchmakers, and answered the crisis with the ultra-thin calibre 240 in 1977 and the 33-complication Calibre 89 in 1989. As President he gathered the company into one manufacture at Plan-les-Ouates in 1996, opened the Patek Philippe Museum in 2001, and created the Patek Philippe Seal in 2009. Under his stewardship annual production grew from around 5,000 watches to around 40,000, and the modern culture of collecting owes him more than most collectors know. Philippe Stern was honoured across the industry when he passed away this June, at 88. His son Thierry, the fourth generation, has led the company since 2009, and still personally approves the sound of every minute repeater.