Audemars Piguet Royal Oak 4100ST Review

THE FIRST LOOK

Audemars Piguet Royal Oak 4100ST First Impressions

What hits you the moment you pick up the 4100ST.

The Audemars Piguet Royal Oak 4100ST is smaller in the hand than photographs prepare you for and better finished than its price suggests. Set it next to the modern Audemars Piguet watches in a display case and the first thing that registers is light behaviour. The bevels running down the bezel flanks, the mirror-polished chamfers between brushed surfaces, and the eight screws sitting dead flush all catch light in a way current production does not quite replicate, because this case was finished when the Royal Oak was still a low-volume object made by a very small company. The second thing that registers is mass, or rather the absence of it. At 35mm across and roughly 7.2mm thick, the Audemars Piguet Royal Oak 4100ST feels closer to a piece of jewelry that happens to keep time than to a steel sports watch.

*below image from Christie's Auctions

Then you notice the seconds hand, and if you know the Royal Oak line at all, it stops you. Known in the Audemars Piguet archives as the Royal Oak III and drawn by Jacqueline Dimier rather than by Gerald Genta, this was the first Royal Oak fitted with a central seconds hand. That thin steel sweep across the Petite Tapisserie field changes the personality of the watch entirely. The 5402 sits still and stares back at you. The 4100ST is alive on the wrist, and that small animation is the reason a lot of collectors who came for the size stay for the dial.

THE WEARING EXPERIENCE

How the Audemars Piguet Royal Oak 4100ST Wears

How the 4100ST actually sits, day in and day out.

The Audemars Piguet Royal Oak 4100ST measures 35mm across the bezel, roughly 44mm from lug tip to lug tip and about 7.2mm thick, and those three numbers work together better than any one of them reads on paper. The octagon is wide relative to the dial opening, so visual presence lands closer to a 36mm or 37mm round watch. The integrated bracelet leaves the case flat and immediately wraps, which means there is no dead space between the case and your wrist the way there is on a lugged watch of similar diameter. In practice it suits wrists from roughly 6 inches to 7.25 inches. Under 6 inches it starts to overhang because of the bracelet's first link geometry. Above 7.25 inches it reads as deliberately small, which for a lot of buyers in 2026 is the entire point.

Thickness is where the 4100ST separates itself from almost everything else you might cross-shop. At 7.2mm it passes under a buttoned dress cuff without snagging, and because the bracelet tapers hard from the case toward the clasp, the weight sits centred on top of the wrist instead of swinging around it. It is genuinely light. Long-day comfort is excellent provided the bracelet has been sized correctly, and this is the one caveat worth stating early: a Royal Oak bracelet with no micro-adjustment is only comfortable when the link count is right. Get that wrong and the head slides. Get it right and you forget you are wearing it, which after four decades is a strange thing to say about a watch that helped invent the luxury steel sports category.

SHOP THIS WATCH

Shop the Audemars Piguet Royal Oak 4100ST

Browse authenticated Audemars Piguet Royal Oak watches available now at WatchGuys.

If a 35mm case at 7.2mm thick sounds like the right answer for your wrist, here is what we currently have available. Every vintage Royal Oak we list is inspected in house, checked for bracelet stretch and dial originality, and backed by the WatchGuys 2 Year Warranty.

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THE DETAILS

Audemars Piguet Royal Oak 4100ST Specifications

Breaking the 4100ST down component by component, and what each one tells you about condition.

Audemars Piguet Royal Oak 4100ST Case and Bezel

The Audemars Piguet Royal Oak 4100ST case and bezel are one assembly rather than two, and understanding that is the key to inspecting one. The eight hexagonal screws are through-bolts: they pass down through the octagonal bezel and fasten with nuts on the caseback side, clamping the crystal and gasket in between. That construction is why the screw heads on an honest example sit perfectly flush and align consistently, and why a badly serviced watch shows screws proud of the bezel surface or rotated out of alignment.

Finishing follows the original Royal Oak grammar. The bezel top is satin brushed, the eight bevels around its edge are mirror polished, and the transition between them should be a crisp line you can feel with a fingernail. On a case that has been polished, that line softens into a rounded shoulder and the octagon loses its geometry, which is the single fastest way to tell an original case from a refinished one. The crystal is sapphire, flat and undistorted. The caseback is solid steel, so there is nothing to admire on the reverse, and the crown on early examples is a push-in design rather than a screw-down, which is exactly why you should treat the water resistance rating as splash protection and nothing more. Later 4100 production fitted with the Caliber 2124 and 2125 gained a screw-down crown, a meaningful practical upgrade if you intend to actually wear the watch daily. The 4100 was also produced in two-tone as the 4100SA and in yellow gold as the 4100BA, and both trade differently from steel, so if the warmer metals appeal, our gold Audemars Piguet watches are the place to start.

The Petite Tapisserie Dial on the Audemars Piguet Royal Oak 4100ST

The Audemars Piguet Royal Oak 4100ST dial is a Petite Tapisserie field, the fine small-square pattern shared with the 5402 rather than the coarser Grande Tapisserie used on modern 41mm references. Under a loupe the pyramids are tiny and razor sharp, and in ambient light the dial reads almost solid, then breaks into texture the moment you tilt it. Applied baton indices sit on a stepped chapter ring, the hands are simple faceted batons filled with tritium, and the AP logo at 12 o'clock appears in a notably small font on early production, a detail collectors use as a dating cue. The date sits at 3 o'clock, colour matched, with no cyclops over it.

Dial condition drives value on this reference more than any other factor. Black, slate grey, blue and silver are the standard colours, and blue examples have become the most requested configuration in recent years, which is worth knowing if you are shopping blue Audemars Piguet dials generally. Black dials that have shifted to warm brown, the so-called tropical examples, command a substantial premium and are the reason two apparently identical 4100ST watches can be twenty thousand dollars apart. What you are checking for is evenness. Genuine tropical fade is uniform and the tapisserie texture stays intact. Moisture damage is patchy, dulls the pattern and often bleaches the printing. Tritium plots should be consistently aged across all markers and the hands should match them, since mismatched tones usually mean replaced hands.

Audemars Piguet Royal Oak 4100ST Bracelet and Clasp

The Audemars Piguet Royal Oak 4100ST bracelet is the component that will decide whether you are happy with the watch in six months. It is fully integrated, hand finished with the same brushed-top and polished-bevel treatment as the case, and it tapers aggressively from the case toward an AP-signed folding clasp. That taper is what makes the watch wear so elegantly, and it is also what makes it fragile. Links are held by friction pins and pressed sleeves, and after four decades of wear the tolerances open up. The result is stretch, visible as gaps between links when you hold the watch horizontally by the clasp.

There is no micro-adjustment and no on-the-fly extension, so fit is set entirely by link count. Sizing is coarse compared with any modern bracelet, and if you sit between two link counts, you will notice it. Replacement links for this generation are difficult to source and expensive when they surface, and a full service bracelet from Audemars Piguet, which carries a later skeleton-style clasp, changes both the look and the collectibility of the watch. An original, correctly stamped clasp on a bracelet with minimal stretch is worth paying up for.

EXPERT TIP | Robertino Altieri | WatchGuys CEO

What I Check First on a Pre-Owned 4100ST

"Hold it flat by the clasp and look down the length of the bracelet. If you can see daylight between the links, that watch has stretch, and there is no cheap fix. Then I run a fingernail along the bezel bevels. Sharp edge means original case. Soft rounded edge means somebody put it on a wheel. Those two checks take fifteen seconds and they move the price by five figures."

UNDER THE HOOD

Audemars Piguet Royal Oak 4100ST Movement Review

How the movement performs where it matters: on the wrist, every day.

The Audemars Piguet Royal Oak 4100ST runs the automatic Caliber 2123, a thin Jaeger-LeCoultre derived movement adapted by Audemars Piguet to add a central seconds hand alongside the date. Later production moved to the Caliber 2124 and 2125. Expect roughly 40 hours of power reserve, which in practice means a watch you wear Monday through Friday will be running Saturday morning and stopped by Sunday afternoon. Accuracy on a healthy, recently serviced example typically lands within a few seconds a day either side of zero, which is respectable for a movement of this generation but is not modern chronometer territory, and anyone expecting a Superlative Chronometer style result will be disappointed. Positional variation is more noticeable than on a current caliber, so where you rest it overnight genuinely changes your weekly gain or loss.

In daily use the small things are good. The date is quick-set through the crown, a real convenience on a watch from this period, and it snaps over cleanly just after midnight on a properly adjusted example. The rotor is quiet, with none of the audible spin some vintage automatics develop, and hand-winding through the push-in crown is smooth if slightly gritty by modern standards. The caseback is solid, so none of the movement finishing is visible in normal use, which is a fair trade given that this caliber was decorated to a functional rather than exhibition standard. The real ownership consideration is not performance, it is parts. Servicing intervals of five to seven years are sensible, and you want a watchmaker who has handled this family before, because sourcing a correct-period component for a 2123 is not the same exercise as sourcing one for a modern caliber.

EXPERT TIP | Robertino Altieri | WatchGuys CEO

Ask What Caliber Is Actually Inside It

"Plenty of 4100s that went through official service came back with a later movement fitted instead of the original. The watch runs fine, sometimes better. But a collector paying a premium wants the period-correct caliber, and the two things are not worth the same money. Always ask for a photo of the movement and the service paperwork before you wire funds."

MARKET VALUE

Audemars Piguet Royal Oak 4100ST Price

What the 4100ST costs right now, and why identical-looking examples trade so far apart.

The Audemars Piguet Royal Oak 4100ST occupies an unusual position in the market: it is a genuinely scarce vintage piece from a brand whose modern output is anything but scarce. Audemars Piguet archive figures record roughly 2,721 steel examples sold between 1977 and 1987, with the bulk of that volume in the first four years, and the wider 4100 family across steel, two-tone and gold totalling more than 8,400 watches. Clean steel examples generally trade between roughly $22,000 and $35,000. Exceptional pieces, meaning unpolished cases with sharp bevels, original bracelets with no measurable stretch, strong tropical or blue dials, and archive paperwork, clear that band comfortably and occasionally approach double the low end.

The direction of travel has been upward. Two forces are pushing it. The first is the broad return to smaller cases, which has taken every well-designed 34mm to 36mm vintage watch with it. The second is arithmetic: a modern steel Royal Oak Jumbo trades in the sixty thousand dollar range, and buyers looking at that number increasingly notice that the watch which first proved the octagon worked in a wearable size costs a third as much and was built in a fraction of the numbers. That said, this is a vintage watch, and it should be bought as one. Liquidity is thinner than for a modern reference, condition dictates everything, and the spread between a good example and a tired one is far wider here than on any current production Royal Oak.

EXPERT TIP | Robertino Altieri | WatchGuys CEO

Get the Extract Before You Buy, Not After

"On a watch this old, the original box and papers are usually long gone. An Extract from the Archives from Audemars Piguet confirms the case number, the caliber and the year it was sold, and it costs a fraction of what it adds to resale. If a seller will not order one or will not wait for one, ask yourself why."

HEAD TO HEAD

Audemars Piguet Royal Oak 4100ST Comparison

The 4100ST against the three watches buyers actually cross-shop it with.

Audemars Piguet Royal Oak 4100ST vs. Audemars Piguet Royal Oak 14790ST

This is the decision most buyers in this segment are actually making. The Audemars Piguet Royal Oak 14790ST is the 36mm successor from the mid 1980s onward, and it is the more practical watch by a clear margin: a screw-down crown, genuine water resistance, a more robust bracelet and a later caliber that is far easier to service. It also trades at a similar level, currently around $30,000 for a good example, so this is not a budget decision. What you give up is period. The 4100ST is a 1970s watch with the small AP logo, the earliest midsize case geometry and a production run of under 3,000 steel pieces. The 14790 was made in far greater numbers over a much longer run. If you want to wear it hard, buy the 14790ST. If you want the reference that established the midsize Royal Oak, buy the 4100ST.

Robertino's Take

"I have sold both, repeatedly, and the customers split cleanly. The 14790 buyer wants a vintage Royal Oak they can live with. The 4100ST buyer wants the one that came first. Neither is wrong. But I will say this: the 4100ST in honest, unpolished condition is getting genuinely hard to find, and the 14790 is not. Scarcity eventually shows up in the price."

Audemars Piguet Royal Oak 4100ST vs. Audemars Piguet Royal Oak 15202ST (Jumbo)

The modern Audemars Piguet Royal Oak 15202 is the reference most people mean when they say they want a Royal Oak, and at 39mm and 8.1mm thick with the ultra-thin Caliber 2121, it is the closest modern descendant of the original 5402. It is also roughly double the money and a fundamentally different watch on the wrist: broader, flatter across the dial and considerably more present. The 4100ST gives you the same design vocabulary and comparable case finishing in a package that disappears rather than announces. For a full breakdown of the modern Jumbo experience, our Audemars Piguet Royal Oak 15202OR review covers the rose gold version in detail. The honest summary: the 15202ST is the better investment-grade asset, the 4100ST is the better value and the more wearable watch.

Audemars Piguet Royal Oak 4100ST vs. Patek Philippe Nautilus 3800/1A

Anyone shopping vintage integrated-bracelet watches at this level eventually looks at both. The Patek Philippe Nautilus 3800/1A is the midsize Nautilus produced from 1981, at 37.5mm and 7.65mm thick, and it plays the same trick of hiding a sports watch under a cuff. It is the softer, rounder, more discreet of the two, where the 4100ST is angular and deliberately architectural. The Patek also costs considerably more, generally from around $50,000 upward for a clean steel example, and it has appreciated faster over the past year. Choose the Nautilus if you want the quieter object and the stronger brand-level liquidity. Choose the 4100ST if you want the sharper design and roughly half the outlay.

THE BOTTOM LINE

Is the Audemars Piguet Royal Oak 4100ST Worth It?

Is the 4100ST worth your money?

Yes. The Audemars Piguet Royal Oak 4100ST is worth buying, provided you buy a good one and you understand what you are buying. This is a 45-year-old watch with a scarce production run, case and bracelet finishing executed to a standard that volume manufacturing has since made uneconomic, and proportions that suit contemporary taste better than almost anything Audemars Piguet currently sells. At roughly a third of the cost of a modern steel Jumbo, it is the most design-per-dollar available anywhere in the Royal Oak line.

It is perfect for the buyer who wants an integrated-bracelet icon that fits under a cuff, who values originality over invulnerability, and who is comfortable owning a watch that needs to be looked after rather than abused. It is the wrong watch for someone who wants a single do-everything piece: there is effectively no water resistance on early examples, the tritium is long dead so it is useless in the dark, the bracelet has no micro-adjustment, and parts availability is a genuine constraint. The single strongest reason to buy one is condition-driven scarcity. Unpolished 4100ST cases with sharp bevels and tight original bracelets are already difficult to find, and every year that passes makes them harder. If you want to handle one before deciding, you can see an Audemars Piguet Royal Oak in person with one of our specialists.

Robertino's Take

"The 4100ST is the Royal Oak I tell people to buy when they say they love the design but cannot get comfortable with 41mm or with sixty thousand dollars. Buy the condition, not the deal. I would rather pay thirty two for an unpolished one on a tight original bracelet than twenty two for a project. On this reference, cheap gets expensive fast."

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