Short answer
Most listings for a replica Omega De Ville Trésor 18k sell gold-plated steel. Plating depth runs from about 1 to 5 microns. Solid 18k gold is 750 parts gold per 1000 by weight. At 2025 gold prices near $2,600 per troy ounce, a solid 18k case carries $1,500 to $2,500 of metal on its own.
The genuine watch
Omega sells the De Ville Trésor in 40 mm and 36 mm cases. Metals include steel, Sedna gold, Moonshine gold, Canopus gold, and platinum. Omega lists calibre 8910 in the 40 mm Master Chronometer version. Gold cases carry the 750 fineness stamp and Swiss hallmarks. Reference numbers change with dial and metal, so two watches can share a case size and carry different numbers.
What 18k means in the replica market
Three products get sold under that label.
- Gold plating: 316L or 904L steel with a thin gold layer. Common on $150 to $400 listings.
- Gold filled or rolled gold: a bonded layer of at least 1/20 of total weight under US rules. Rare in this market.
- Solid 18k: a full 750 alloy case. Sellers quote $1,800 and up for these, and most do not exist.
Ask which one. A seller who cannot answer sells plating.
Weights and numbers to compare
18k yellow gold has a density near 15.5 g/cm3. Stainless steel sits near 8.0 g/cm3. A solid gold Trésor case weighs close to twice the steel case of the same size. A 40 mm steel Trésor lands around 60 to 70 grams on a bracelet. A solid 18k version runs near 100 grams or more.
Plated replicas often weigh within 5 grams of the steel original. That is the tell.
Checks that cost nothing
- Look for the 750 stamp and the Swiss hallmark near the caseback lugs.
- Weigh the watch on a kitchen scale. Under 75 grams means plating.
- Check caseback engraving depth. Laser etching looks shallow and flat.
- Test with a jeweler XRF gun. Surface readings under 50% gold mean plating.
Price bands
Genuine 18k Trésor models retail from about $15,000 to $30,000 USD. Replica listings cluster at $180 to $500. Solid 18k cases at those prices are not possible. The raw metal costs more than the asking price.
Legal points
US Customs and Border Protection can seize counterfeit watches at import. Trafficking in counterfeit goods carries criminal penalties under 18 U.S.C. 2320. FTC jewelry guides require sellers to label plated items as gold plated and to state the plating thickness.