Start at the caseback. A genuine Vacheron Constantin in gold carries a matched set of stamps: the maker's mark, the gold purity mark, and a reference and serial number that agree with the papers and with the movement. If those items do not line up, stop there. Plated brass and gold-filled fakes fail this check first, and no dial detail makes up for a bad caseback.
1. Read the caseback stamps
- Clean the caseback and photograph it under raking light with a phone set to macro.
- Find the purity mark. Swiss 18k gold uses the head of a Saint Bernard dog, or the mark 750. Older pieces may show a scale mark.
- Compare the maker's mark to the Vacheron Constantin Maltese cross punch used in the year of production.
- Write down the reference number and case serial, then check the reference against the case size and material listed for that model.
- Ask a watchmaker to open the back and read the movement number. The three numbers should belong to the same watch.
2. Weigh the case
18k gold sits near 15.5 g per cubic centimeter, so a solid gold case has real mass. Weigh the watch head on a jeweler's scale and compare it with the published weight for that reference. A fake in plated steel or brass comes in light, often by 15 to 30 percent. Check the lugs and the caseback edge for wear that shows a copper or gray base metal under the surface. A magnet should not pull on a gold case; a strong pull means steel underneath.
3. Study the dial and hands
- Use a 10x loupe on the printing. Genuine text sits sharp and raised, with no halo or bleed at the edges.
- Check that the applied hour markers and hands are gold, not gold-tone. Look at the edges for flaking.
- Compare the Maltese cross and the word mark against a known photograph of the same reference.
- Read the date window font and the alignment of the aperture. Fakes sit crooked or use a wrong typeface.
4. Inspect the movement
Most gold Vacheron Constantin watches since the 1990s have a display back. Look for Geneva stripes cut with a straight, deep grain, polished bevels on the bridges, and a hand-engraved rotor. Fakes use stamped bridges with shallow lines and printed text. Check the engraving depth with a loupe; laser printing sits flat, while genuine engraving catches light from different angles.
5. Trace the paperwork
A genuine set includes the certificate of origin with the reference, case number and movement number written to match the watch. Service receipts from an authorized center carry the same numbers. Call the boutique named on the papers and ask them to confirm the serial. Fakes ship with printed cards and blank warranty books.
6. Get a second opinion before you pay
Ask for an inspection at a Vacheron Constantin boutique or an independent watchmaker who carries the brand. Meet at the counter, not in a parking lot. Use an escrow service for remote deals so funds release after the inspection clears.