Patek Philippe CH 28-520 Caliber & Nautilus 5711, 5980

The Patek Philippe Reference 1518 holds a significant place in horological history as the world's first perpetual calendar chronograph produced in a series. Introduced in 1941, it established a foundational complication for the brand, preceding other notable perpetual calendar chronographs such as the 2499 and 3970. This reference is recognized for its pioneering role in combining these two complex mechanisms in a wristwatch.

This reference was primarily offered in yellow gold, with a limited number produced in rose gold and an even smaller quantity in stainless steel. The case typically measures 35mm in diameter, housing the manual-winding caliber 13''' Q. The movement features a column-wheel chronograph mechanism integrated with the perpetual calendar complication. The dial often presents with applied Arabic numerals or bâton indexes, and a tachymeter scale on the outer periphery.

For collectors, the 1518 represents a landmark Patek Philippe reference, highly sought after for its historical importance and rarity, particularly examples in alternative metals. Its design language and technical sophistication set a precedent for subsequent perpetual calendar chronograph models, making it a cornerstone for understanding the evolution of this complication within the brand's catalog.

The Patek Philippe Reference 2499 is a highly significant perpetual calendar chronograph, representing a pivotal model in the brand's history of complicated wristwatches. It succeeded the Reference 1518 and introduced a larger case diameter and updated aesthetic, establishing a design language that would influence subsequent perpetual calendar chronographs from Patek Philippe for decades. The reference was produced in four distinct series, each with subtle variations in dial layout, pusher style, and case construction.

This reference typically features a case crafted from precious metals, most commonly yellow gold, though examples in rose gold and platinum are known. The case diameter is generally 37.5mm, housing a manual-wind movement, specifically the caliber 13''' Q. This movement integrates a perpetual calendar mechanism with a chronograph function, offering indications for day, date, month, leap year, and moon phases. The crystal is typically acrylic for earlier series and sapphire for later iterations.

The 2499 is highly sought after by collectors due to its rarity, complexity, and historical importance. It is considered a benchmark for vintage complicated Patek Philippe watches and represents the evolution of the perpetual calendar chronograph from the mid-20th century. The variations between the four series provide distinct collecting opportunities, with each series possessing unique characteristics that appeal to different connoisseurs.

The Patek Philippe reference 3700 is recognized as the original Nautilus model. It established the distinctive porthole-inspired case design and integrated bracelet that define the collection. This reference was produced for a significant period, laying the foundation for subsequent Nautilus iterations and solidifying its place in the brand's sports watch offerings.

This reference features a stainless steel case measuring 42 mm in diameter and 7.6 mm in thickness, fitted with a sapphire crystal. It houses the self-winding Caliber 28-20 C, which provides a power reserve of 45 hours. The watch is water-resistant to 120 meters and typically presents with a blue dial, offering a date complication.

The 3700 appeals to collectors interested in the foundational pieces of significant watch lines. It represents the initial vision for the Nautilus, preceding later mid-size and complicated versions. Its production run from 1976 to 1990 saw various dial and bracelet configurations, making specific examples of interest to those studying the model's evolution.

The Patek Philippe reference 3970 is a perpetual calendar chronograph, a complication central to the brand's heritage. It succeeded the highly regarded reference 2499 and served as a bridge to the later reference 5970. The 3970 was produced over an extended period, allowing for several series and subtle variations in its design, making it a significant model for collectors interested in the evolution of Patek Philippe's complicated wristwatches.

This reference features a 36mm case, commonly found in 18k white gold, yellow gold, rose gold, and platinum. It is powered by the manual-wind caliber CH 27-70 Q, based on a Lemania ébauche, which offers a power reserve of 60 hours. The watch is fitted with a sapphire crystal, protecting a dial that typically includes subdials for the chronograph, perpetual calendar displays, and moon phases.

The 3970 appeals to collectors seeking a classic Patek Philippe perpetual calendar chronograph with a traditional aesthetic and a historically important movement. Its long production run from 1986 to 2004 means that examples from different series, such as the first, second, and third, exhibit minor differences in dial layout and case details, providing distinct collecting opportunities within the reference.

The Patek Philippe reference 5035 introduced the annual calendar complication to the brand's regular production lineup, marking a significant development in accessible high horology. This reference automatically accounts for months with 30 or 31 days, requiring manual adjustment only once a year at the end of February. Its introduction provided collectors with a sophisticated calendar function that was more practical for daily wear than a perpetual calendar, yet still showcased Patek Philippe's technical prowess.

The 5035 features a 37 mm case, offered in 18k yellow gold, white gold, or rose gold, with a smooth bezel. It is powered by the automatic caliber 315 S IRM QA, which includes a power reserve indicator, date, and small seconds. The movement provides a power reserve of approximately 45 hours. A sapphire crystal protects the dial, and the watch is water resistant to 25 meters.

This reference appeals to collectors seeking a historically important Patek Philippe annual calendar. Its design is characterized by a balanced dial layout, typically in silver, with sub-dials for the month, day, and date, along with a power reserve indicator. The 5035 was produced from 1996 to 2006, establishing the annual calendar as a core complication within the Patek Philippe collection.