Fake Speedmaster 42mm: The Short Answer

A fake Speedmaster 42mm is a counterfeit built to the footprint of the Omega Speedmaster Professional Moonwatch, the hand wound chronograph Omega lists at a 42 mm case diameter. The number matters because the Moonwatch is the most copied Speedmaster, and because a watch that measures 39 mm across the case is not a Moonwatch copy at all. It is usually a copy of the smaller Speedmaster Reduced, or a generic chronograph wearing Speedmaster dial printing.

Three things separate a cheap knockoff from a well built 1:1 replica: the movement inside, the placement of the three subdials, and how the case measures under a caliper. Case diameter on its own tells you very little. A watch can hit 42 mm and still be wrong everywhere a collector looks.

Before You Start

  • A digital caliper, or a ruler and a steady hand
  • A loupe or a phone camera with macro mode
  • Reference photos of an authentic 42 mm Moonwatch shot from the same angles

Measure the Case the Right Way

Set the caliper jaws across the case at 9 and 3 o'clock, excluding the crown and the pushers. An authentic 42 mm Moonwatch reads close to 42.0 mm there. Lug to lug runs about 47 to 48 mm depending on the reference, lug width is 20 mm, and thickness lands between 13 and 14 mm. Replicas usually fail on thickness first, because a slim case is the cheapest way to cut cost, and it changes how the watch sits on the wrist.

Checks That Expose a 42mm Fake

  1. Look at the subdial positions. A Moonwatch has counters at 3, 6 and 9 o'clock: a 30 minute counter at 3, a 12 hour totalizer at 6, running seconds at 9. Nothing sits at 12 o'clock.
  2. Check for a date window. The Speedmaster Professional has no date. A window at 3 or 4:30 is the fastest way to end the conversation.
  3. Press the top pusher and watch the chronograph seconds hand. Mechanical versions sweep in small steps. A quartz movement jumps once per second or stutters.
  4. Inspect the tachymeter scale. It should sit on the bezel insert, not printed under the crystal. The numerals need even spacing and a clean mark at 12.
  5. Read the dial text under magnification. Look for OMEGA above the Omega symbol, with Speedmaster and PROFESSIONAL below center. Uneven kerning, thick serifs, or a squashed symbol are common on fakes.
  6. Compare the hands. Baton hour and minute hands, with a thin sweep seconds hand carrying a flat counterweight.
  7. Turn the watch over. The caseback should carry the seahorse medallion and the NASA flight qualification line. Engraving should be cut deep, not laser printed on the surface.
  8. Weigh it in your hand. A steel 42 mm Moonwatch on a bracelet has real mass. Hollow cases feel light and ring hollow when tapped.
  9. Wind the crown. Hand winding should feel smooth with a faint ratchet. A gritty, silent, or locked crown points to a battery.

What Is Actually Inside

Most 42 mm fakes run one of three movements. The Seagull ST19 is a hand wound column wheel chronograph with a layout close to the original, so the subdials often land in the right places. Valjoux style 7750 movements push the counters toward 12 and 6, which is why so many fakes show a subdial at 12. Quartz movements are the bottom tier and the easiest to catch by eye. A real Moonwatch is hand wound only, so any automatic or battery powered version is wrong by definition.

Fit and Proportions

42 mm is a wide case paired with a 47 to 48 mm lug to lug span, which is why it wears larger than the number suggests. A 6.5 inch wrist will see the lugs reach the edges. If a seller quotes 42 mm but the watch sits flat and small on a 7 inch wrist, the case was measured with the crown included or the listing is simply wrong.

Buying Checklist

  1. Ask for measured case diameter, thickness, and lug to lug in millimeters, not a photo alone.
  2. Ask which movement the watch uses and whether the chronograph is mechanical or quartz.
  3. Ask for a straight on photo of the caseback.
  4. Ask for a macro shot of the dial text at 12 o'clock and the tachymeter mark at 12.

Bottom Line

Judge a fake Speedmaster 42mm by measurement, subdial layout, and movement type, in that order. Get those three right and the rest of the watch is a matter of finishing quality, not basic accuracy.