The short answer
The IW371489 is the IWC Portugieser Chronograph Edition "150 Years" in stainless steel. It has a white lacquered dial with blue numerals, a 40.9 mm case, and the caliber 79350 chronograph movement. Replicas of this reference sell for about $180 to $600 in online listings. Three things separate a close copy from a poor one: dial printing, subdial position, and case thickness.
Genuine specifications
- Reference: IW371489
- Model: Portugieser Chronograph, Edition "150 Years"
- Case: stainless steel, 40.9 mm diameter, about 12.3 mm thick
- Lug width: 20 mm
- Dial: white lacquer, blue printed numerals and minute track
- Hands: leaf shape, blued steel
- Subdials: small seconds at 6, chronograph minutes at 12
- Date: window at 3
- Movement: caliber 79350, automatic, Valjoux 7750 base, 28,800 vph, 44-hour power reserve, 31 jewels
- Crystal: domed sapphire with antireflective coating
- Water resistance: 3 bar (30 m)
- Strap: black alligator leather, steel pin buckle
IWC sold the watch as a limited edition. Press coverage from 2018 cites a run of 2,000 pieces. Not every listing states that number.
Check the dial first
Dial flaws show up at arm's length. The white lacquer on the genuine watch is flat and slightly warm, not bright paper white. Blue printing sits toward navy. Copies often print a brighter blue that reads as royal blue under daylight.
The two subdials sit on the center vertical line. On the real dial, the gap between the subdial edge and the center hand post is even top and bottom. Replicas shift the 12 o'clock counter up or down by a fraction of a millimeter, and the gap looks wrong.
Hands are blued steel, so they reflect light at an angle and go near-black head on. Painted hands stay the same blue from every angle.
Measure the case
Use calipers. The genuine case measures 40.9 mm across, without the crown. Thickness lands at 12.3 mm. Many copies run 1 mm to 2 mm thicker because the movement stack sits higher under the crystal. Lug width should be 20 mm exactly.
Check the curve of the lugs and the polish on the case flanks. The case sides take a brushed finish, the bezel takes a polish. Copies often polish both.
Ask about the movement
The caliber 79350 beats at 28,800 vibrations per hour. A sweep that looks coarse points to a 21,600 vph movement. Ask for a short video with the second hand visible and the caseback removed.
A stock Asian 7750 puts running seconds at 9 o'clock. A copy with running seconds at 6 needs a modified movement or a transfer gear. Ask the seller which one. A reply that dodges the question is an answer in itself.
Chronograph start, stop, and reset should feel firm. Reset while the chrono runs and the genuine movement blocks the action. A copy with a weak reset can jam.
Caseback and engraving
The display back shows a rotor with Geneva stripes and the IWC name. Engraved reference numbers sit on the outer ring. On copies, the engraving is shallow and the font is wider than the original.
Price tiers
- $180 to $260: entry tier, painted hands, thick case, 21,600 vph movement
- $300 to $450: better dial printing, correct case size, 28,800 vph clone
- $500 to $600 and up: closest dial color match, corrected subdial spacing, sapphire with coating
Legal note
Counterfeit watches are illegal to sell in the United States under the Trademark Counterfeiting Act. US Customs and Border Protection can seize shipments at import. Buying carries risk of loss with no recourse.