The latest grail category in luxury watches does not involve a specific design or function, but a material: Hard stone dials have become one of the most sought-after — and hardest to find — elements of both new and vintage timepieces.

Although hard stone dials are too rare to be labeled a trend, they’ve popped up in the highest circles of watchmaking often enough recently to bear notice. One of Rolex’s most talked-about releases last year, for example, was the Oyster Perpetual Day-Date 36 with turquoise, green aventurine or carnelian dials ($58,000-$63,000), while Cartier used mother-of-pearl, turquoise and onyx for the Mini Baignoire Marquetry ($81,500). Piaget’s quirky but elegant Hidden Treasures watch with a turquoise dial (price on request) won the ladies’ category in the 2023 Grand Prix d’Horlogerie de Genève, the industry’s annual awards event. Zenith used chalcedony for the Defy Extreme Glacier ($26,100), to evoke the blue-white look of an iceberg. (Only 50 or fewer of all these watches will be produced.) And at the end of January, H. Moser & Cie is scheduled to introduce a tourbillon with a face of rare Wyoming jade ($119,000).

“We have customers who understand what it is to have access to extraordinary pieces,” said Guillaume Chautru, head of gemology at Piaget. “They know it takes time. They sometimes ask me to find a stone for a dial, and I say, ‘Listen, I can get probably one stone that fits our standards every 10 years.’ They say, ‘OK, we’ll pay. We’ll wait.’”

Piaget pioneered the use of hard stone dials in the 1960s, but the style fell out of favor in the 1970s, when the emergence of quartz watches made inexpensive watches with little decoration into a fad.

Stone dials have been produced only periodically since then, and in very limited quantities. Occasionally, however, examples pop up at auction, where they have commanded high prices.

“Collectors, now more than ever, appreciate rarity, which includes watches with uncommon features like ornamental dials,” said Paul Boutros, who is deputy chairman, watches, as well as head of watches, Americas, for the auctioneer Phillips in New York City. “They command significant premiums compared to watches with regular dials.

“At our Geneva sale last November, an F.P. Journe Optimum with a jade dial sold for 533,400 Swiss francs [around $626,000], over an estimate of 200,000 to 400,000 francs. Had the watch been fitted with a standard dial, we would have estimated it at 40,000 to 80,000 francs and would likely have achieved a result of less than half the jade dial version.”

Rock to Paper Thin

The more sweat and tears involved in creating an object, the more desirable it becomes, and there is plenty of both in making hard stone dials. The process requires patience, skill and a rigorously dust-free, temperature-controlled environment: Open a window at the wrong time and some minerals will crack. Close the door to the safe too hard and they might shatter.

Work starts with a hunk of stone, called rough, which is dug up — and the supply is not limitless. Some mines, including the top quality Sleeping Beauty turquoise mine in Arizona, have been shuttered for years. While some suppliers managed to buy huge stocks before closures, only a small portion of those holdings would produce the high grade stone required. As Mr. Chautru said, “You could have all the right equipment, all the right skills. But if you don’t have the rough, forget about it.”

First, the rough is sliced into squares so that brands or their dial makers can use templates to determine how best to cut slices for dials. Piaget, for example, requires malachite to be cut so the matrix (the mineral’s veins and color variation) is aligned in a certain way. “We need it to be cut with the vein curving upwards, like a smile,” Mr. Chautru said. “But not too smiley, just not sad.”

Even when cuts are successful, drilling the dial pieces for date displays or subdials can cause breakage. Also, those cuts must be accurate to within fractions of a millimeter.

“We work with tolerances of plus/minus 0.01 millimeters for the outside diameter and holes,” said Sandra Ripp, co-chief executive of Groh + Ripp in Idar-Oberstein, Germany. She is a fourth-generation member of her family to run the company, which specializes in making mineral dials.

By the time the stone slices are given their final polish, they are 0.4 millimeters to 0.10 millimeters thick, depending on the material.

Scratch It, Lose It

At Groh + Ripp, there are strict handling protocols and the workshop must be spotless. “It’s rare that you can eat from the floor in a workshop, but in ours, you can,” Ms. Ripp said. “It’s very important to work clean, because any small piece of dirt could scratch the surface. You need specialized training from the beginning of the process to the end.

“Some stones are softer than others — turquoise and malachite are delicate. My grandfather used to say, ‘All you have to do is look at malachite and it will break.’”

If a slice is just scratched, it cannot be used, and considering the cost of materials and skilled labor, discarding a single slice worth thousands of dollars would be a problem.

After the final polish, the slices are delivered to the brand or dial maker for gluing to metal dial plates, an exacting process that also can easily go wrong.

“At Piaget, we use carefully calculated quantities of glue for each dial, depending on the material, the design and the size,” Mr. Chautru said. “If you use too much, there is too much pressure on the stone, and it breaks. Mastering our gluing process alone took 10 years of development.”

A Slice Adds Life

Watches with hard stone dials can be any style: vintage, modern, even gender fluid, giving makers a range of creative freedom.

“Back in the ’60s, it was used in very different designs from what we see today,” said Edouard Meylan, chief executive of H. Moser & Cie, with headquarters in Schaffhausen, Switzerland. “I love dials that are vibrant, and the color you get from some of these minerals is outstanding.

“We are seeing a huge demand, because hard stones are not only rare, but require an extra level of knowledge and craftsmanship, using specially designed tools. People love that. So do I.”

The company’s new limited edition tourbillon has dials made of jade from Wyoming (it intends to make 50 this year, and 100 in total). Its artisans are working with slices 0.6 millimeters thick, drilled at the 6 o’clock position so the wearer can see the tourbillon mechanism beneath.

“Hopefully we get something that is still in one piece by the end of the process,” Mr. Meylan said.

From Mother Earth

The dial is not the only use of hard stone in contemporary design.

Zenith’s Defy Extreme Glacier, for example, used faceted chalcedony on parts of the case and for the crown protector. The model was part of a limited-edition series celebrating outdoor adventure, and chalcedony’s icy-blue translucence was meant to evoke icebergs.

“Hard stones are painful to work with,” Romain Marietta, Zenith’s director of product development and heritage, said. “If you scratch it, the stone is ready for the bin. Once you assemble the watch, it’s quite robust, but it’s still a stone. If you drop it on the floor, the stone could break.”

The next edition in the series is to have a tiger’s-eye dial, in keeping with a jungle theme. Both are planned to be limited to 50 pieces each.

And designs don’t have to be symmetrical.

The turquoise dial of Piaget Hidden Treasures, for example, is partially covered by pink gold, sculpted to appear as if the metal has been torn away. If you like the idea, and want to buy one, you may have to wait a few years and then trawl auction catalogs.

How many will Piaget make? “Honestly, I don’t know,” Mr. Chautru said. “Not many, for sure, because of the level of quality we require for the turquoise — it has to have perfect, consistent color, with no spots; it’s so pure, it almost looks like plastic.

“There will be just a few pieces, for sure. We will see what Mother Earth can provide for us.”