Answer first: the 3700/11 is the original Jumbo Nautilus, a 42mm steel watch Gerald Genta designed for Patek Philippe in 1976. Replicas of this exact reference do exist, but they are a niche build. Most factories put their money into the 5711, which is thicker, easier to machine and far more in demand. That means a lot of what gets sold as a 3700/11 is a 5711 with a different listing title, or a Nautilus case that is two millimetres too thick.
What the 3700/11 actually is
The Nautilus launched in 1976 as reference 3700, and the digits after the slash are Patek's own code for the bracelet and metal combination. A 3700/11 is generally described as a bracelet variant of the same Jumbo case rather than a separate watch, which is why photos of a /11 and a /1A look almost identical until you reach the clasp.
The dial is where you learn the reference by heart. Blue-black, horizontally grooved, no seconds hand, date window at three, and a signature that sits high. The case is 42mm across, about 7.6mm thick, and the bracelet is integrated, so the first link is part of the case and the taper runs continuously to the clasp.
Why this reference is hard to copy well
Thin cases are unforgiving. Every fraction of a millimetre shows up on the wrist, and a 9mm case wearing a 7.6mm dial and bezel looks inflated from across a table. The original used calibre 28-255 C, a thin automatic based on the Jaeger-LeCoultre 920, and thin movements cost money. Builders who want to sell at a normal price use whatever fits, then hide the extra height in a domed caseback.
The other problem is finishing. The 3700 mixes brushed flat surfaces with polished bevels, and the line between them has to be crisp. On cheaper builds the bevel goes soft, the brushing wanders, and the bracelet links rattle instead of sitting tight.
What I check, in order
- Case thickness. Ask for a caliper photo across the caseback, not the seller's spec sheet.
- Dial grooves. They should be even in depth and cut straight, with no blurring near the date window.
- Date font and position. On the 3700 it sits close to the edge, not floating toward the middle of the dial.
- Bezel shape. The original is rounded, not faceted, and should look soft from the side rather than slab-sided.
- Bracelet taper and flex. Integrated bracelets either articulate smoothly or they feel like a hinge.
- Crown and engraving. The crown sits flush against the case, and the caseback markings are shallow and clean.
Movements, prices and expectations
There is no single best version of this watch. What exists is a small number of builders who get the case profile right and a much larger number who do not. Expect the thin case to cost more than a 5711 replica of the same quality, and expect to send it for a service within a couple of years if it runs on a budget automatic.
Buy the measurements first and the photographs second. If the seller cannot tell you the thickness, the lug-to-lug, and the movement inside, the rest of the conversation will not get better.