The IWC Portugieser Hand-Wound Tourbillon Day & Night, reference IW545901, pairs a flying minute tourbillon with a day-and-night display in a 42.4 mm 18 ct Armor Gold case. Its black dial and black Santoni alligator strap give the manually wound watch a restrained look, while IWC’s calibre 81925 provides an 84-hour power reserve. Here is what the specifications establish—and what they do not.
What defines the IW545901?
This Portugieser brings together two complications: a flying minute tourbillon and a day-and-night display. IWC’s published specifications identify the display by function, but do not provide enough detail to explain its mechanism or how its indication is read. The tourbillon is the more visually prominent complication, set against a black dial with applied Arabic numerals.
IWC describes the Portugieser collection as combining dress-watch elegance with functional roots in maritime timekeeping and navigation. The brand says its applied Arabic numerals are attached individually by hand; these are manufacturer descriptions, not independent performance findings. IWC’s Portugieser Tourbillon collection page provides that broader context.
Case, dial and wear dimensions
- Case: 18 ct Armor Gold.
- Diameter: 42.4 mm.
- Height: 10.8 mm.
- Dial: black.
- Strap: black Santoni alligator leather, 22 mm wide, with an 18 mm buckle width.
The case is topped by a convex sapphire crystal with anti-reflective coating on both sides. A see-through sapphire back displays the movement. IWC lists water resistance at 6 bar on its Swiss product page. These are the manufacturer’s stated specifications, not results from an independent water-resistance test. The Swiss-market IW545901 page lists the complete model specifications.
#1 Best Overall
- IWC Da Vinci Automatic Unisex Watch IW459306
Calibre 81925 and the tourbillon
IWC’s in-house calibre 81925 is manually wound and specified with an 84-hour power reserve. The movement runs at 28,800 vibrations per hour (4 Hz) and comprises 195 components and 22 jewels.
A tourbillon places the regulating components inside a rotating cage. IWC explains that the complication was originally designed to offset gravitational error in pocket watches and says that today it mainly serves an aesthetic function. The brand also says continuous rotation can contribute to a more precise rate. Those statements describe IWC’s explanation of the complication; no independent accuracy test of the IW545901 is established here, so they should not be read as a measured performance claim for this watch. IWC’s product information for the reference includes its tourbillon explanation.
Rank #2
- IWC Portugieser Chronograph Automatic Men's Watch IW371624
The watch also has a hacking tourbillon mechanism. IWC lists that function, but the available model specifications do not explain its operation in further detail.
Strap options and fit
The supplied strap is black Santoni alligator leather. IWC says alternate straps are available for select models, but a nominal 22 mm width alone does not guarantee that a replacement will fit: check the lug dimensions and buckle compatibility for the specific strap, along with its material and construction.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Rank #3
Price and source context
IWC’s Swiss product page lists the IW545901 at CHF 86,000 including VAT. That is the price shown on the Switzerland-market page, not a universal price or a statement about availability in other markets. The manufacturer specifications establish the watch’s configuration and stated features; published launch-era coverage from Hodinkee and Monochrome Watches provides additional secondary context.
Quick Recap
Rank #4
- IWC Portugieser Chronograph Automatic Black Dial Men's Watch IW371609
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
