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Top-tier supplier movement · caliber IWC Cal. 79350: Valjoux 7750 base, IWC-modified, 28,800bph, 44h PR, 25j; retains 7750 cam switching (no column wheel), IWC-finished rotor; used in Portugieser Chrono 3714 · 44h power reserve
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
41 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

The Portugieser Chronograph uses a Valjoux 7750-based movement with added column wheel; the sub-register layout and slim case profile are the primary authentication anchors.

Known issues in the market
  • Cal. 79350 is a Valjoux 7750 with IWC column-wheel modification; a watchmaker will see the 7750 architecture, which is legitimate for this reference but often misunderstood by buyers.
  • The sub-register layout follows the 7750 architecture: 12 o'clock shows 30-minute counter; 6 o'clock shows running seconds; buyers expecting a different layout have the wrong reference.
  • Domed sapphire crystal on the slim case must be original; a flat replacement crystal changes the profile of the watch significantly.
  • Earlier IW3714 references have slightly different case geometry than later IW371446 production; mixed case/movement generations occur on service-reassembled watches.
AreaWhat to checkWhat is correctRed flag
dialSub-register positions (7750 layout)30-minute chronograph counter at 12 o'clock; running seconds sub-register at 6 o'clock; no sub-register at 3 or 9; silver or black dial with railway-track minute chapter ringRunning seconds at 3 and 30-minute counter at 9 (standard 7750 layout, indicating non-IWC-modified movement); any sub-register at 9 on the claimed IW371446
crystalDomed sapphire crystal profilePronounced dome visible in profile; blue anti-reflective coating; dome height matches the slim case; IWC logo etching on crystal at 6 visible under polarized lightFlat crystal indicating replacement; absent or mismatched AR coating; no IWC crystal etching; crystal that sits below the case bezel level
movementCal. 79350 column wheel via casebackValjoux 7750 architecture with IWC column-wheel modification visible; "IWC" signed rotor; "Cal. 79350" text; 44-hour power reserve; column wheel at correct positionStandard cam-lever 7750 without column wheel (indicating a non-IWC-modified movement); "IWC" absent on rotor; Cal. 79350 text absent
caseSlim case proportions and pusher feel41mm diameter; slim profile (approximately 13mm thick); two pushers at 2 and 4 snap crisply; lug shape consistent with Portugieser family; screw-down casebackCase thickness over 14mm; spongy pushers; lug shape inconsistent with Portugieser profile; case diameter outside 40.5-41.5mm
dialIWC font and text quality"IWC SCHAFFHAUSEN" at 12 in correct serif font; "PORTUGIESER" text below; sub-register text at correct size and weight; Arabic numeral 6 replaced by 6 o'clock sub-registerIncorrect font weight; "SCHAFFHAUSEN" absent or misspelled; sub-register text that does not match the dial color family
Common legitimate replacements
  • Leather straps (brown leather is most common) are regularly replaced on this reference.
  • Domed sapphire crystals are sometimes replaced after impact damage; a replacement flat crystal is a condition issue worth noting.
Expert resources: IWC authorized dealers authenticate via serial. The Watchuseek IWC board and IWCwatches.com cover Portugieser Chronograph authentication. A watchmaker can confirm the column-wheel modification to the 7750 base.

Authentication guide

Last reviewed June 2026

The IW371446 Portugieser Chronograph uses a silver dial with a Valjoux 7750-based Cal. 79320. The 40.9mm case has the characteristic thin lugs and thin bezel of the Portugieser family. The Portugieser is the most replicated IWC line; dial printing quality is the first inspection point.

Known reproduction risks

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HIGH RISK

Replica Portugieser Chronographs with incorrect dial text and hand color

  • Replica dials use the wrong shade of off-white or silver; genuine IWC silver dials have a specific warm-white appearance
  • Blued hands on replicas are frequently painted; the reflection under a direct light source reveals the difference
  • Register subdial spacing and sizing are often incorrect relative to the dial layout on genuine examples
  • Applied numerals on replicas are frequently less crisp at the edges under 10x magnification

The Portugieser is the most replicated IWC family. Approach any Portugieser purchase without provenance documentation as requiring thorough inspection.

MEDIUM

Non-original dial in a genuine case

  • Aftermarket silver dials may show slightly different text positioning or font weight relative to genuine IWC production
  • Date wheel color inconsistency when present

Dial variants by era

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EraDescriptionIdentifiers
2000s to present (IW371446)Silver dial with two-register chronograph layout at 3 and 9. Applied Arabic numerals at 12, 3, 6, and 9; applied baton indexes at other positions. Blued steel hands.
  • Two-register chronograph: 30-minute counter at 3 o'clock, 12-hour counter at 9 o'clock
  • Blued steel hands (hour, minute, chronograph seconds, sub-register hands)
  • Applied gold-tone Arabic numerals and baton indexes
  • "PORTUGIESER CHRONOGRAPH" text at 6 o'clock on the silver dial
  • Small seconds integrated into the hour counter at 9

Service part flags

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Movement

Original: Cal. 79320, based on Valjoux 7750 with modifications for the two-register layout. The three-register standard 7750 layout is reworked to suppress the small seconds subdial at 9 and integrate it differently.

Replacement tells
  • A standard Valjoux 7750 with three registers showing, indicating the IWC conversion parts are missing
  • Service documentation noting a non-IWC caliber number
  • Chronograph registers in a different position than 3 and 9 o'clock
Blued hands

Original: The hands are chemically blued; the color should be a uniform deep blue with no bronze or rainbow banding.

Replacement tells
  • Hands that are black-painted or lacquered rather than blued; blued steel reflects light differently from painted hands
  • Hands with inconsistent color suggesting non-factory bluing or replacement with non-blued hands
  • Hands that appear too thick for the slender Portugieser profile

Case back markings

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2000s to present
  • Solid steel caseback
  • Engraved: IWC SCHAFFHAUSEN
  • Reference IW371446 and serial number
  • No soft iron inner case on the Portugieser (anti-magnetic cage is a Pilot line feature)
  • Movement is visible through an exhibition caseback on some variants; check that the Cal. 79320 is what is present

Movement tells

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  • Cal. 79320 runs at 28,800 bph. The column-wheel chronograph mechanism is IWC-modified from the standard 7750 lateral cam; it is not identical to the base ETA movement.
  • The rotor is IWC-marked; a bare ETA/Valjoux rotor without IWC finishing indicates a service replacement or unrestored movement.
  • Power reserve is approximately 44 hours; a significantly shorter run-down suggests mainspring wear.
Sources: IWC Portugieser product page; WatchUSeek -- Portugieser Chrono IW371446 reference thread.

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