A fake Speedmaster 40mm fails on three checks: subdial spacing, caseback detail, and movement type. Genuine 40mm Speedmasters come from the Speedmaster Date, Day-Date, and Racing lines, and each one carries a fixed dial layout plus a numbered Omega movement. Run those three checks in order and most fakes break at the first one.
One size claim settles the rest. The Moonwatch Professional is 42mm, the Reduced is 39mm, and the Speedmaster 38 is 38mm. A seller who advertises a "40mm Speedmaster Professional" is describing a size Omega never used for that line.
Which Speedmasters Are Actually 40mm?
Omega has built several 40mm Speedmaster families, and each has its own references, movements, and dial layout.
- Speedmaster Date: 40mm, date window at 3, Valjoux 7750 base movement, sapphire caseback on most references.
- Speedmaster Day-Date: 40mm, day and date at 3, same movement family as the Date.
- Speedmaster Racing: 40mm in the 2010s series, chronograph with a textured dial.
- Speedmaster '57: 40.5mm on the modern calibre 9906 version, so it lands near 40mm but is not 40mm.
The Speedmaster Date is the model most fakes copy, because the case shape reads close to a Moonwatch in photos.
How to Spot a Fake Speedmaster 40mm
Subdial spacing and layout
On a genuine Speedmaster Date, the subdials sit at 12, 9, and 6, with the date at 3. The subdial hands rest in the center of their rings, and the rings carry crisp, even hash marks. Fakes crowd the subdials toward the middle of the dial, which leaves a wide empty band near the outer edge.
Chronograph hand behavior
Start the chronograph and watch the center seconds hand. A mechanical movement that beats at 28,800 vibrations per hour sweeps in small steps. A quartz fake jumps one full second at a time. Every 40mm Speedmaster family listed above is mechanical, so a ticking hand is a fail.
Caseback and movement
Most 40mm Speedmaster Date references have a sapphire caseback, so the movement is part of the display. A genuine watch shows a decorated rotor with the Omega symbol, the calibre number, and striped or circular finishing. A solid steel caseback on a model that should have a display back is a warning sign.
Ask for a clear photo of the movement before money moves. Owners of real watches send that photo without a fuss, and a refusal tells you plenty.
Dial printing, logo, and lume
The Omega symbol and the OMEGA word mark are applied metal on most 40mm references, with sharp edges and a polished face. Fakes print the logo, which looks flat through a loupe. Lume plots on a real dial sit inside clean metal frames and glow with an even tone.
Case, crown, and pushers
Measure the case with calipers across the 3 and 9 positions, with the crown left out of the number. A 40mm reference should read 39.8 to 40.2mm. Many fakes land at 39mm or 41mm, or hit 40mm only when the crown is counted.
Check the pushers as well. They should sit flush with the case band, snap back with a firm click, and show no scratches around the base.
Bracelet, clasp, and end links
End links on a genuine Speedmaster sit tight against the case with no gap and no rattle. The clasp carries a stamped Omega symbol and a bracelet code, and the link pins match the reference. Loose end links and a shallow clasp stamp point to a fake.
Reference Numbers, Papers, and Serial Checks
Every Speedmaster carries a reference number on the caseback and a serial number on the movement. Those two need to match the model you think you are buying, and the warranty card needs to carry the same serial.
- Find the reference number and check it against the Omega product archive.
- Request a movement photo that shows the serial number.
- Compare the movement serial with the one on the card.
- Have a watchmaker open the case before you pay.
Boxes and papers get faked too, so treat them as a secondary check rather than proof.
Why 40mm Fakes Are Common
Omega stopped making most 40mm Speedmaster Date and Day-Date references, so buyers cannot walk into a store and compare a real one against a used listing. The 40mm size also suits wrists that a 42mm Moonwatch overwhelms. That gap between demand and supply is where fakes live.
What If You Already Bought a Fake?
Act fast and keep the paper trail. Save the listing, the messages, and the payment record before you contact the seller.
- Ask for a refund in writing and give the seller a clear deadline.
- If you paid by card or a buyer-protected service, open a dispute with photos of the movement and caseback.
- Report the listing to the platform and, in the US, to the FTC or your state consumer protection office.
- Do not resell the watch as genuine. That turns a bad purchase into a legal problem.
FAQ
Is there a real 40mm Omega Speedmaster?
Yes. The Speedmaster Date, Day-Date, and Racing lines all include 40mm references, and the modern Speedmaster '57 measures 40.5mm.
What is the fastest way to spot a fake Speedmaster?
Start the chronograph and watch the center seconds hand. A one-second tick means quartz, and no genuine 40mm Speedmaster Date, Day-Date, or Racing reference runs on quartz.
How much should a genuine 40mm Speedmaster cost?
Used 40mm Speedmaster Date and Day-Date watches sell well below Moonwatch prices, but the number moves with condition, service history, box, and papers. Check completed sales on a watch marketplace instead of trusting a single listing.
Can a jeweler authenticate a Speedmaster 40mm?
Any watchmaker who services Omega can open the case, identify the movement, and confirm the serial against the reference. Pay for that service and ask for a written note you can show a seller or a disputes team.