Omega De Ville Trésor Co-Axial 40mm at a Glance
The De Ville Trésor Co-Axial Master Chronometer 40mm is Omega's slim dress watch, built around a hand-wound caliber and a case roughly 10.5mm thick. Steel and gold versions share a 40mm diameter, a 20mm lug width, and a lug-to-lug distance near 48mm. The Trésor name dates to 1949 and Omega revived it as the formal end of the De Ville line: thin profile, minimal dial, leather strap, and no date window on most references. For wrist fit, the 48mm lug-to-lug measurement tells you more than the 40mm diameter does.
What Separates a Trésor From Other De Ville Models
The Trésor stands apart through its movement type rather than its dial decoration. The 40mm version runs on caliber 8928 or 8929, both hand-wound, both co-axial, and both certified by METAS as Master Chronometer. That certification covers precision, magnetic resistance to 15,000 gauss, and power reserve testing on the finished watch, not just the movement design. Water resistance is 30 meters, which is normal for a dress piece and not suitable for swimming.
Specifications to Confirm Before Buying
- Case diameter 40mm, thickness about 10.5mm, lug width 20mm
- Hand-wound caliber 8928 or 8929, co-axial escapement
- Master Chronometer certification by METAS, 8-year warranty from Omega
- Domed sapphire crystal with anti-reflective treatment inside
- Exhibition caseback with a sapphire window, 30m water resistance
- Dial options: plain, sun-brushed, or diamond-set indices depending on reference
How to Verify a Genuine Example
- Write down the reference number engraved on the caseback and look it up in Omega's online catalogue.
- Match the movement number on the caseback to the number printed on the warranty card and the Master Chronometer certificate.
- Open the Omega account page and register the watch; a genuine serial will either register or come back as already sold by an authorized dealer.
- Inspect the caseback engraving under a loupe; factory text has crisp, evenly spaced lettering with no burrs.
- Wind the crown slowly and feel for a smooth, even take-up with no grinding or dead zone.
- Place the watch on a demagnetizer test card or a phone magnetometer app to confirm the movement stays accurate near a strong magnetic source.
- Request the original box, warranty card, and METAS certificate as one set, and photograph each item before payment.
Sizing and Wearing Notes
A 40mm case with a 20mm strap wears larger than the numbers suggest when the lugs are long and straight. Wrists under 16.5cm often fit better on a smaller Trésor reference. The strap is a quick-release type on recent versions, so aftermarket bands are easy to swap without tools. This guide covers the authentic Omega reference and the documents that should travel with it.