Short answer first
"Fake Zeitwerk 306.104" is a search phrase that leads to listings, forum posts and photo sets, all using the same number as if it were a factory reference. It does not belong to the block of numbers A. Lange & Söhne publishes for the Zeitwerk family, and I have not found it in any official catalogue entry. Treat 306.104 as a seller's code. When a watch is offered under it, the number on the page proves nothing, so you have to judge the piece itself: the dial windows, the movement, the case back engraving and the paperwork.
What the real Zeitwerk is
The Zeitwerk is Lange's digital-display watch. Instead of hands, it shows the hour and the minute in two separate windows with numerals that jump rather than sweep. Under the dial sits a hand-wound movement with a constant-force escapement that stores energy and releases it in steps, which is what makes the jump instant instead of a slow creep. It is made in Glashütte, in gold or platinum, and it is one of the harder watches in the world to copy well. That difficulty is exactly why the fakes look wrong at the windows.
Why 306.104 keeps showing up
Replica sellers borrow real reference numbers and then add digits, because a long specific number makes a listing feel official. The same number gets copied from one listing to the next, then quoted in forum threads, and after a while it reads like a real model. In other cases it is a dealer stock code, an internal case number, or a number engraved on the case back by whoever assembled the watch. None of those are the same thing as a reference number.
Dial and case tells
- The jump. A genuine Zeitwerk snaps the minute numeral over in an instant. Fakes either creep, hesitate, or use a printed disc behind a stencil window, so the numeral sits slightly off centre.
- Window edges. Look at the frame around the hour and minute apertures. On the real thing the edges are crisp and polished, with no burr and no visible glue.
- Printing. The brand name, the "Made in Germany" line and the scale text should be sharp under a loupe, not fuzzy or slightly raised.
- Case metal. Hallmarks and gold content stamps should be clean and correctly placed. Laser etching looks shallow and grey.
- Weight and feel. Solid gold has a density that a plated case does not, and the crown action should be smooth rather than gritty.
Movement checks
Ask a watchmaker to open it, not the seller. Lange finishing is a signature in itself: a three-quarter plate with Glashütte ribbing, blued screws, gold chatons and a balance cock that is hand engraved. Machine engraving is shallow, repetitive and too even. Replicas usually hide a stock automatic or a basic hand-wound calibre behind a decorated plate, and the jumping mechanism is the first thing to disappear. If the seller will not allow an inspection, that answers your question.
Case back, serials and papers
Lange engraves the reference and the case number on the case back, and both should match the certificate that came with the watch. Replicas often have a number that matches nothing, or a certificate printed on the wrong stock. Ask for the service history, the original box and the papers, and be sceptical of a full set that arrives without a service record on a watch of this age.
Price is the loudest signal
A genuine Zeitwerk trades in the tens of thousands of dollars on the secondary market. Anything asking a few hundred, or a few thousand, is not that watch, whatever the listing says. Check completed sales rather than asking prices, and compare like for like on metal, condition and box and papers.
Before you pay
- Ask for the reference number in writing and check it against the maker's own model list.
- Request macro photos of the numeral windows, the case back engraving and the movement.
- Buy with an authentication clause, or have an independent watchmaker inspect it before money changes hands.
- Walk away from any seller who blocks those steps.
One last point. Buying a replica as a replica is a choice you make for yourself. Buying one that is being sold as a genuine Lange is a different matter, and in most places that is fraud. Know which one you are looking at before you send money.