A fake Patek Philippe 3700 is a counterfeit copy of the original 1976 Nautilus, and it usually fails on three checks: case thickness, bracelet construction, and the movement. A genuine 3700/1A is a 42 mm steel monobloc case only about 7.6 mm thick, running the ultra-thin Jaeger-LeCoultre based caliber 28-255 C. Counterfeits tend to be 1.5 to 3 mm thicker, use a plated case, and hide a quartz or ETA movement behind a cosmetic rotor.
What Is the Patek Philippe 3700?
The 3700/1A launched in 1976 as Patek Philippe's first steel sports watch, drawn by designer Gérald Genta. It carries an integrated bracelet, two lateral "ears" on the case flanks, an uncluttered dial with no seconds hand, and horizontal embossed grooves across the surface. Original examples now sell at auction well into six figures, which is exactly why counterfeits exist.
What Gives a Fake Patek Philippe 3700 Away?
- Case thickness. A real 3700/1A measures roughly 7.6 mm. Most fakes cannot fit a decorated movement inside that envelope, so they add height that is visible on the wrist and under calipers.
- Dial grooves. Genuine horizontal grooves are crisp, evenly spaced, and catch light in a continuous band. Fakes show soft, wavy engraving with uneven gaps near the date window.
- Date and fonts. The date aperture on a genuine watch sits tight and square with a period-correct wheel. Fakes use oversized windows, off-center alignment, and lettering that is too bold.
- Bracelet links. The original bracelet tapers in precise steps and holds sharp, polished bevels. Counterfeit links are often stamped, thinner, and rattle at the clasp.
How Thick Should a Genuine Nautilus 3700 Be?
A real 3700/1A sits at about 7.6 mm from crystal to caseback. Measure with a digital caliper and confirm the crown sits nearly flush with the case flank. If the watch reads 9 mm or more, stop there, because no authentic 3700 was built that tall.
Why Do the Bracelet and Caseback Matter Most?
The 3700/1A uses a monobloc case, so the movement is removed from the dial side rather than through a screw-down back. Fakes almost always use a conventional screw-in caseback, which is the fastest tell once you look closely. Genuine casebacks also carry reference and serial engravings that are shallow, precise, and stamped rather than laser-etched.
How Does the Movement Expose a Counterfeit?
Caliber 28-255 C is an ultra-thin automatic with Geneva stripes, polished bevels, and a free-sprung Gyromax balance wheel. Counterfeits show a rotor with printed text instead of engraved plates, and often a balance cock with a regulator arm that no Patek caliber would have. A watchmaker can confirm the caliber and finishing in minutes.
Are Replica Patek Philippe 3700 Watches Legal?
Selling or importing a counterfeit watch that carries another brand's trademark is illegal in the United States and most other markets. Buying one privately also carries risk, since counterfeits can be seized in transit and hold no resale value. A watch described as genuine but priced far below market is counterfeit, not a bargain.
What Should You Check Before Paying for a 3700?
- Request a caliper photo showing total case thickness.
- Confirm the reference and serial numbers, then order an Extract from the Archives from Patek Philippe.
- Inspect whether the caseback is monobloc or screw-down.
- Have an independent watchmaker verify the caliber and dial originality before funds move.
- Buy only from an established auction house or dealer with a written return policy.
Digital references and aftermarket "tribute" watches exist in the same search results, but neither is a 3700/1A. The reference number, the monobloc case, and the 7.6 mm height are the three facts that separate a real Nautilus from a copy.