Quick answer
A fake Tourbograph perpetual calendar is a replica that pairs a visible tourbillon with a multi-function calendar display. Most of these watches cannot do the one job that defines a perpetual calendar: advance from February 28 to February 29 in a leap year without correction. The fastest check is to set the watch to February 28 of a leap year, move the hands past midnight, and read the date window. If the date shows March 1, the calendar is simple or annual, not perpetual. Everything else on the watch is secondary to that result.
Prerequisites
- A 10x loupe and a bright, diffused light.
- Reference photos of the genuine A. Lange & Söhne Tourbograph Perpetual Pour le Mérite: front, back, and profile.
- A calendar corrector pin with a wood or plastic tip. Never use metal.
- A stopwatch, and a timegrapher if you have one.
- Permission from the owner before touching any caseback or corrector.
Inspection procedure
- Match the dial layout to the reference. Count the subdials, note where the date and month apertures sit, and compare the hand shapes and printed text to photos of the genuine piece. A shifted aperture or a wrong subdial count ends the inspection.
- Run the leap-year test. Set the calendar to February 28 of a leap year such as 2028, then advance the hands past midnight. A perpetual calendar jumps to February 29 and keeps the day, month, and leap indicator in step. A replica with a simple date wheel rolls to March 1.
- Check every calendar function by hand. Advance the day, date, month, and moonphase with the correctors one at a time. A genuine calendar module moves each disc with a firm, short travel. Stiff correctors, skipped teeth, or a moonphase that does not track 29.5 days point to a cosmetic calendar plate.
- Time the tourbillon cage. Watch the carriage for 60 seconds against a stopwatch. A one-minute tourbillon turns once per minute, starting and finishing at the same point. A cage that finishes early, lags, or stops is a decorative rotor of no horological value.
- Look inside the cage with the loupe. Check where the balance wheel sits. In a real tourbillon the balance and escapement ride inside the rotating carriage. If the balance sits on a fixed bridge and the cage spins around nothing, the watch has an open-heart dial, not a tourbillon.
- Measure the case profile. Replica calendar modules add about 2 to 4 mm of height and change the lug angle. Lay the watch next to the reference profile photo and compare thickness at the center and the curve of the lugs.
- Inspect the correctors and pushers. Genuine perpetual calendars set each function with a recessed corrector sunk into the case flank. On replicas these are often plain drilled holes, uneven in depth, with rough edges. Press each one and note the travel and the sound.
- Read the movement through the display back. Check engraving, screw slots, jewel settings, and the shape of the bridges against the reference. Replica finishing looks flat, with sharp edges and printed text where the genuine movement carries hand engraving.
- Run it for 24 hours on a timegrapher. Note rate, amplitude, and beat error before and after a full wind. Replica tourbillons often deliver 30 to 40 hours of reserve and drift 20 to 40 seconds per day.
- Compare the asking price to the market. A genuine Tourbograph Perpetual sells in the high six figures. Any watch offered at a small fraction of that, with a photocopied certificate, is counterfeit.
Legal note
In the United States, trafficking in counterfeit goods is a federal crime, and customs officers seize counterfeit watches at the border. Buying a replica is not the same as buying a watch, and reselling one as genuine is fraud. Use this procedure to identify or authenticate a watch you own or have been asked to inspect.