Short answer
405.031 is a reference number from A. Lange & Söhne, not a model name. Lange writes references as six digits, and the first three group the watch into a family. The 405 group covers the Datograph Up/Down, a flyback chronograph introduced in 2012. Searches for "Lange 2" are loose shorthand for the second-generation Datograph. Copies of this reference exist in small numbers. None of them reproduces the movement.
What the number points to
A. Lange & Söhne lists the Datograph Up/Down in a platinum case of 41 mm, with a black dial and a power-reserve display. The movement is calibre L951.6: hand wound, column wheel, horizontal clutch, flyback function, and a minute counter that jumps in one step. Frequency is 2.5 Hz (18,000 vph). Power reserve is 60 hours. The case back is sapphire. Retail prices for the reference have run from the high five figures to the low six figures, set by metal and year of sale. Platinum examples have traded on the secondary market for about $50,000 to $85,000.
Lange does not publish total production. Independent estimates put annual output near 5,000 watches.
Why Lange copies stay scarce
Replica output follows brand volume. Rolex, Audemars Piguet and Patek Philippe sell hundreds of thousands of watches a year, so tooling costs spread across a large market. Lange sells a few thousand. The Datograph adds a second problem: the chronograph mechanism. A column wheel, a horizontal clutch and an instant-jump minute counter cost real money to build. Copying a case is cheap. Copying the movement is not.
What the replica versions use
- Case: 316L steel with rhodium plating, sold as "platinum". Platinum has a density of 21.45 g/cm3. Steel is 7.85 g/cm3. A platinum case weighs about 2.7 times as much as a steel case of the same size.
- Movement: in most cases a Seagull ST19 hand-wound chronograph, a design derived from the Venus 175. It beats at 3 Hz (21,600 vph) with a power reserve of about 40 hours.
- Dial: printed text, flat subdials, and a power-reserve hand that tracks the mainspring instead of stepping like the original.
- Finish: no Glashütte ribbing on the plates, no engraved balance cock, no gold chatons with blued screws.
Prices for these copies sit between about $200 and $800. Claims of a Swiss movement at that price do not hold up.
How to check a watch sold as genuine
- Ask for the reference and serial on the case back, then compare against the Lange catalogue.
- Request macro photos of the movement. Gold chatons, blued screws and hand engraving on the balance cock are the markers.
- Check the weight. A platinum Datograph feels heavier than any steel copy.
- Ask for service papers. Lange's service center can confirm a watch it has handled.
- Treat a below-market price as a signal. A complete platinum example under $40,000 is a warning, not a bargain.
Legal position in the United States
18 U.S.C. § 2320 makes trafficking in counterfeit goods a federal crime. A first offense carries up to 10 years in prison and a $2 million fine for an individual. 19 U.S.C. § 1526 lets Customs and Border Protection seize and destroy imported goods that carry a counterfeit mark. Personal use is not an exception. Selling a copy as genuine adds fraud and Lanham Act claims on top.
Open points
No public data exists on how many Lange copies are made or which workshops build them. Factory names used on resale forums change each year. The exact metal and dial combinations tied to 405.031 should be checked against Lange's own catalogue, because dealer listings mix reference numbers across the Datograph line.