Short answer
A fake Datograph Up/Down is a replica of the A. Lange & Söhne Datograph Up/Down, a hand-wound chronograph that Lange released in 2012 as an update of the 1999 Datograph. The real case measures 41mm across and 13.1mm thick. It holds calibre L951.6: a column-wheel chronograph with flyback, 60 hours of power reserve, an outsize date at 12 o'clock, a 30-minute counter at 4 o'clock, small seconds at 8 o'clock, and a power reserve hand at 6 o'clock. No replica copies the L951.6. Replicas copy the outside of the watch.
Datograph Up/Down Review: 1:1 Replica Comparison
Numbers to compare
- Diameter: 41mm. A replica that measures 39mm uses the older Datograph case.
- Height: 13.1mm. Many replicas run 14mm to 15mm because the movement sits taller.
- Power reserve: 60 hours. The hand at 6 o'clock tracks an arc scale.
- Date: two discs behind one window, split at the centre line.
- Weight: platinum is denser than steel and gold. A platinum head weighs more than a steel head of the same size.
Where replicas fall short
- Movement. The real watch has a column wheel, a horizontal clutch, and a flyback. Replica chronographs use a Seagull ST19 or a Valjoux-type layout. The pusher action feels soft at start and stop.
- Power reserve. On many replicas the hand at 6 o'clock is fixed. Others link it to a day and night disc. It does not read the mainspring.
- Date. The two discs can sit at the wrong gap. The numeral font can differ. Some replicas print both numbers on one disc.
- Finish. Lange engraves the balance cock by hand. Replicas use a stamp or a laser etch. Screw heads are painted or chemically blued.
- Dial. Print on replica dials looks fuzzy under a 10x loupe. The minute track edges blur.
Checks before you buy
- Ask for a caliper photo on the case, in millimetres.
- Ask for video of the chronograph running, then resetting to zero.
- Ask for two photos of the power reserve hand: at full wind, and after 24 hours. A working indicator moves.
- Look at the date window. The split between discs should meet at the centre.
- Confirm the layout: minute counter at 4, small seconds at 8.
- Ask for the weight in grams. A steel replica of a platinum watch is a mismatch.
What no replica copies
Lange finishes parts that sit behind the caseback. Gold chatons, polished bevels, and the engraved cock take hours of hand work. A replica finishes the parts a camera can reach. A replica is not a Lange, and resale value is close to zero.