In the world of high watchmaking, beauty is more than surface deep.

Some of the most exquisitely decorated parts of a watch are right there on the dial, but many can’t be seen unless you flip the watch over and look at the movement through an open caseback. Still others, including the work on components that go a long way to justifying a six-figure price, can be seen only by the watchmaker who assembles the movement.

But all of this embellishment is what the industry calls finissage, the art of skilled hand work on the movements and dials. And it has the power to keep connoisseurs and watchmakers chatting into the wee hours, debating the merits of such arcana as polished screw heads and chamfered bridges.

When it comes to luxury watches, the obsession with chronometry — timekeeping accuracy and the length of the power reserve — often overshadows the art of finish, but to a growing circle of watch lovers and makers, finish is everything.

For example, the independent watchmaker Kari Voutilainen, a nine-time winner of the prestigious Grand Prix d’Horlogerie de Genève awards, is a champion of finissage. When asked why it matters, the soft-spoken Mr. Voutilainen immediately started a detailed discourse on the fine points of pivots.

Pivots are the metallic tips of the pinions that hold in place the wheels of a movement, most crucially the balance wheel. The shape and precise size of each pivot is important because of the potential for friction between it and the bearing that keeps it in place. Too much friction will cause wear and tear, which will degrade other components, affect accuracy and ultimately reduce the life span of the movement.

The only way to properly finish a pivot, Mr. Voutilainen said, is to burnish it, which involves shaping and finishing by hand.

“A trend among industrial watch companies is to not burnish the pivots,” he said during a recent phone interview from his office in St. Sulpice, Switzerland. “Instead, they ‘polish’ them with a ceramic disk, which essentially cuts the metal away, but removing metal weakens the component, whereas if you burnish it, you are squeezing the metal, making it more dense, so it becomes harder.

“Cutting the metal is more efficient, but it’s the lazy way,” he added. “The gears will wear out. I think they feel it doesn’t matter — they will just replace them every time the watch is serviced.”

Like Playing a Violin

At onetime, making a watch meant doing it by hand, because there was no other way. Today, C.N.C. (computer numerical control) machines have taken over a lot of the work that previously was painstakingly done by hand, but a hand finish remains the mark of high watchmaking — and it is not just about aesthetics, it also is about function.

Almost every component in a watch movement works against another component, so when they are finished by hand, with smoother, more precisely calibrated edges, they will last longer, with less need for lubrication, and there will be less chance that the metal used to form them will shed particulates and cause wear on other working parts.

Most types of finish are, in fact, rooted in function: In the days before water-resistant cases, polished and blued screws were oxidized to that color to protect them from moisture damage and deterioration; côtes de Genéve, the name of the fine stripes often engraved on rotors or bridges, was designed to deflect dust; perlage, the circular graining often applied to back plates, was applied because it hides the scratches that can occur during movement assembly and final adjustment.

And because most finishes are rendered by hand, technique is everything. Consider chamfering, sometimes called anglage, which is the art of beveling and polishing the edges of plates and bridges to 45 degrees using a file or a wooden peg and fine abrasives. A perfect, uniform bevel, and especially a rounded bevel, sends aficionados into paroxysms of joy.

“Because it’s done freehand, technique is important and becomes a means of expression, even a trademark of certain watchmakers,” said Gary Getz, a California-based business consultant and avid watch collector.

He identified the independent watchmaker Philippe Dufour as a great master of the art.

“I once saw a video of him doing rounded bevels,” Mr. Getz said. “He was holding a bridge attached to a stick in his left hand, and in his right hand he’s got his file, and he’s filing it, but at the same time he’s moving his left hand back and forth. I was thinking, wow, you can’t get a good result from that. If I were doing it, I’d be putting that bridge in a vice held in concrete rather than just holding it. But he did it perfectly.

“I asked him about it later, and he said, ‘No, it’s like playing a violin. Both the instrument and the bow have to move for the bow to find the string. If you put a violin in a vice and tried to play it, it would sound awful.’”

Carving Out the Wow Factor

Another brand known for its trademark finish is A. Lange & Söhne, the Glashütte, Germany-based brand that hand engraves the balance cock — a small bridge that holds the balance wheel in place — on every watch it makes (about 5,500 a year).

Lange’s director of development, Tony de Haas, described the deep, freehand engraving process as “a modern interpretation of a very classical, traditional floral pattern. Today we engrave deeper and do really nice accents, and the flowering, it’s really sharp and really wow. Sometimes a buyer’s initials can be incorporated in very tiny letters into the design.”

This level of flourish can add hundreds of hours of costly work to a timepiece, and a buyer willing to pay for a hand-finished movement likely expects such a finish on the dial as well.

“It’s like handmade shoes,” Mr. Voutilainen said.

“Of course they have to be comfortable and they fit for the feet they’re made for, but then afterwards they have to look beautiful, well finished, with perfect stitching, and so on,” he said.

“It’s the same with watch dials. The dial finishing is part of the game. You can’t skip it.”

Among the many ways to dress a dial — including enameling, gem setting, engraving, marquetry and hand painting — one of the most difficult techniques to master is freehand engraving.

It’s the specialty of Bovet, a small, boutique watchmaker based in Fleurier, Switzerland. Édouard Bovet, who founded the company in 1822, created an engraving style called fleurisanne, a floral scroll pattern not unlike the design on the Lange balance cock, except that it covers the dial.

Each fleurisanne piece looks slightly different, depending on which of the workshop’s three artisans executes it.

“They are so talented,” Pascal Raffy, Bovet’s owner and chief executive, said. “From time to time, I give them the same subject, and you cannot imagine how every hand is different. The depth of the engraving, the shape of the curves. The three of them have their own interpretations, and this is called art.”

The company produces 1,000 to 1,200 watches a year, 40 percent of which are custom orders.

Getting the Perfect Polish

Talk to watchmakers, though, and they will tell you that the most difficult and demanding finish of all is the art of black polish, a technique that makes a surface intensely shiny.

It is done using a polishing tool and a fine abrasive, such as diamond paste, moving the tool slowly, in a circle, sometimes for hours until the surface is so perfectly flat and shiny that from some angles it looks like a mirror, but from others it looks as if the surface is black.

“It’s difficult because you have to feel the metal and the tool,” Mr. Voutilainen said. “You have to watch the consistency of the paste. Is it getting hard? Is it too sticky?”

Black polish is typically done on the hammers of minute repeaters, a complication that chimes on demand by pushing a button or a slide lever.

The first time that Mr. de Haas tried the process (many years ago), “I think I spent one half day, because I couldn’t get it. It’s a bit of a trick; you have to do it with the right pressure. There were scratches everywhere, and I had to keep polishing them out, and if you polish too much, you lose the 45-degree bevels.

“I showed it to my boss and he says, ‘Yeah, the polishing is good, but you can throw the hammer away now because you polished too much and you’ve lost the angle.’” he said. “Also, the hammer has to have a certain mass, a certain weight, and by then it was too light. I had to start over.”

Once you start to recognize the finer points of a great finish, you cannot unsee them, and you have gone down the rabbit hole of serious connoisseurship. Not only does finish make a watch beautiful, it makes a statement about overall quality.

“When a movement is hand finished, with clean, uniform lines and perfect polish, you get this glow,” Mr. Getz said. “There is a lot of life in it.”