Short answer
'3rd generation' is a seller label, not an Omega term. No factory publishes generation numbers for replica Speedmaster 1957 watches. The same build can be sold as gen 2 by one dealer and gen 3 by another. Treat the number as a claim about a batch, and judge the watch on its own specs.
The watch being copied
Omega released the Speedmaster 1957 Trilogy in 2017 for the 60th year of the model. The Speedmaster in that set is reference 311.10.39.30.01.001. It has a 38.6 mm steel case, 19 mm lugs, broad arrow hands, a lollipop chronograph seconds hand, and a dot over 90 bezel. The dial has no date and no 'PROFESSIONAL' line. The movement is the hand-wound calibre 1861 at 18,000 vph, which is 2.5 Hz. Omega sold the three-watch box as 557 sets. The Speedmaster on its own came as a numbered run of 3,557 pieces.
Where replica builds diverge
- Case size. Many replicas measure 39.5 mm to 40 mm across, against 38.6 mm on the original.
- Beat rate. Budget builds use a Seagull ST19 or a similar Chinese column wheel movement at 21,600 vph (3 Hz). The 1861 runs at 18,000 vph. A timegrapher shows the gap.
- Subdial spacing. The 1861 puts running seconds at 9 o'clock and the 30-minute counter at 3 o'clock. Copies built on other movements move those centers.
- Dial text. Font weight on 'OMEGA' and 'Speedmaster' is a common fault. So is a printed 'PROFESSIONAL' line that the 1957 does not have.
- Bezel. The dot over 90 and the base 500 mark must sit at the right angle. On copies the print is thin or off-center.
- Crystal. The real watch uses a domed sapphire with an inner anti-reflective coat. Copies use mineral glass or flat sapphire with a blue cast.
Checks with no tools
- Measure the case with calipers. 38.6 mm is the target, crown excluded.
- Time the watch for 60 seconds against a reference clock. Count 5 beats per second. If you count 6, the movement is not an 1861 layout.
- Look for a date window. There is none on the 1957.
- Check the lollipop seconds hand. The disc sits at the tip, not mid-shaft.
- Ask the seller for a timegrapher photo with rate, amplitude, and beat error.
Price and limits
Replica Speedmaster 1957 watches sell from about USD 250 to USD 600. Genuine 311.10.39.30.01.001 examples list used between about USD 5,500 and USD 9,000. Prices move with the market, so check current sold listings. No replica carries an Omega serial, a valid warranty, or service support from Omega. Resale value is close to zero.
What is not known
Factory names, batch dates, and the exact changes between 'gen 2' and 'gen 3' are not public. Sellers do not name the source. Claims about a specific generation should be treated as unverified unless the seller shows photos of the actual watch in stock.