Editorial
The 3700/1A is the original Patek Philippe Nautilus, designed by Gérald Genta, launched in 1976, produced through 1990, and the watch that established the integrated-bracelet-sport-watch category that dominates modern collecting half a century later. 42mm (large for 1976), steel, with the famously thin two-piece case construction (the case was supplied by Favre & Perret, the same Geneva case maker who built the Royal Oak's case. Calatrava is a Patek model name, not the case maker, despite the common myth). The 3700's reputation is built on near-religious enthusiast devotion to its proportions and finishing.
Gérald Genta designed the Nautilus in 1974 for Patek Philippe; production began 1976. The 3700/1A is the first-generation reference, with the caliber 28-255 C (a Jaeger-LeCoultre 920 base, same family as the Royal Oak 5402's movement). Production through ~1990, replaced by the 3710 and then the 5711 family.
Variants include 3700/11 (white or champagne dial) and 3700/100 (deeper blue). The 1976 retail was 3,100 CHF, high for a steel sport watch and the rationale behind the famous 'most expensive steel watch in the world' positioning.
Common things to check: dial originality (Patek dials are heavily reluminescent service-replaced, verify the 'Patek Philippe Genève' wordmark printing under loupe; check the indices for crisp gold-applied work); bracelet originality (the H-link integrated bracelet is the Nautilus signature, verify the lug-end and clasp generation match the 3700 era); case finishing (the alternating polish/brush is hand-applied, over-restored examples lose definition); the 'Tiffany & Co' co-signed dials are a meaningful premium and the most-counterfeited variant; papers (a 3700 without Patek extract from the archives in this price bracket is essentially unsellable at market).
