Quick answer

A fake Datograph 912.021 is a replica of the first generation A. Lange & Söhne Datograph, the hand wound flyback chronograph with the outsize date at 12 o'clock. A good replica copies the 39 mm case, the asymmetric dial with subdials near 4 and 8, and the look of an exposed hand wound movement. No replica copies the L951.1 column wheel chronograph, the heft of a platinum case, or the hand finishing on the bridges. Judge the watch against those limits and you will not overpay.

Reference points to compare against

  • Case: round, roughly 39 mm wide and about 12.8 mm thick, stepped bezel, straight lugs.
  • Dial: outsize double date at 12 o'clock, small seconds near 8 o'clock, 30 minute chronograph counter near 4 o'clock.
  • Hands: thin baton style in rhodiumed or blued steel, chronograph seconds in the center.
  • Movement: hand wound, visible through a sapphire caseback, two pushers plus a crown, no rotor.
  • Strap and buckle: alligator with a signed buckle on genuine pieces.

How to evaluate one before you buy

  1. Ask for macro photos of the dial with the watch running, then zoom in on the date font, subdial spacing, and print crispness.
  2. Compare the listed measurements to the reference. A 41 mm case or a 14 mm thickness is a different watch wearing a Datograph dial.
  3. Request a video of the chronograph start, stop, and reset. The central seconds hand should snap back to 12 each time.
  4. Watch the date change. Both digits should sit centered in the aperture and flip together at midnight.
  5. Confirm the movement is hand wound. A rotor visible through the caseback ends the conversation, because the reference has none.
  6. Judge the pusher feel in that same video. Mushy or grinding pushers point to a cheap chronograph module.
  7. Check the crown action. It should wind with a firm click and resist when fully wound, not spin free.
  8. Get the strap and buckle materials in writing from the seller before payment.
  9. Confirm the return window, the shipping method, and who pays return freight.

What the movement will be

Most replicas in this size run a Seagull ST19 based hand wound chronograph or a modified automatic. Both keep time and both drive a working 30 minute counter. Neither offers true flyback, where one press of the lower pusher restarts the chronograph without stopping it first. If a listing claims flyback, test that specific function on video. Expect a decorated bridge plate that reads as busy at arm's length and coarse under a loupe.

Red flags in listings

  • Catalog renders only, with no photos of the actual unit for sale.
  • Origin claims with no movement photo and no caseback shot.
  • Prices far below the normal range for a hand wound chronograph replica.
  • Sellers who refuse a video of the date change or the chrono reset.
  • No stated return policy or payment method with buyer protection.

Takeaway

Buy this replica for the dial layout, the case proportions, and the hand wound feel. Pay for layout accuracy and honest specs, not for claims about origin or precious metal cases. A seller who answers spec questions with fresh photos and a working video has earned the sale.