IWC IW3750 (Pre-owned - Good) — USD 12,500 on eBay

The IWC Da Vinci Perpetual Calendar Chronograph, reference IW3750, was a pivotal model in IWC's history, introduced in 1985. It showcased a groundbreaking perpetual calendar mechanism that could be entirely adjusted via the crown, a significant innovation at the time. This design simplified the setting process for a complex complication, making it more accessible to wearers. The IW3750 features a 42.3 mm stainless steel case, a white dial, and is powered by an automatic movement with a 168-hour power reserve. The watch is water-resistant to 30 meters and protected by a sapphire crystal. It typically comes on a leather strap with a fixed bezel. This reference is notable for its historical importance in the development of perpetual calendars, demonstrating IWC's engineering prowess. Its crown-controlled adjustment system set a benchmark for ease of use in perpetual calendar watches, influencing subsequent designs in the industry.