Short answer
A Speedmaster sold as a "Cal. 9900" is either a genuine Omega (the Speedmaster Racing or a 44.25mm Co-Axial Master Chronometer) or a replica built on a Valjoux 7750 or a Chinese automatic with a chronograph module. No replica runs a real 9900. The giveaway is the movement layout, the pusher feel, and how the chronograph minute hand behaves. You can check all three in about a minute.
What the real Calibre 9900 is
- Automatic chronograph, 25,200 vph, roughly 60 hours of power reserve from two series-coupled barrels.
- Column wheel and vertical clutch, not a cam-and-lever conversion of a base caliber.
- Co-Axial escapement with a silicon balance spring, METAS Master Chronometer certified on watches from 2015 onward.
- Layout: running seconds at 9 o'clock, a combined 60-minute and 12-hour totalizer at 3, date at 6.
That layout is the most useful single fact about this movement. The 9900 family stacks chronograph minutes and hours into one subdial at 3, with two coaxial hands. It is not a three-register movement and it does not put a 30-minute counter at 12.
Tells I check first
Chronograph minute hand
Start the chrono and let it run past the one-minute mark. On a real 9900, the larger hand at 3 o'clock jumps a full minute at once. It does not creep. Replicas on a 7750 base drive that hand through a gear train, so it drifts forward gradually and never lands clean.
Pusher feel and reset
A column wheel with a vertical clutch gives a short, dry, equal click on start and on stop. On most replicas the second push is softer than the first, and the reset has a grainy rattle because the hammers are fighting a running train instead of a disengaged one.
Running seconds position
The small seconds has to be at 9. Plenty of fakes get this right, which is why it cannot be your only test. A sweeping small seconds paired with a slowly drifting chrono minute hand at 3 is the combination that exposes a module movement.
Caseback and rotor
The 9900 is a display-back movement, so you get to look. Genuine rotor engraving is deep and crisp, with the Omega logo, the Co-Axial Master Chronometer wording, and the movement number. Replica engraving is shallow, sometimes laser-etched, and the jewels and screws you see are often decorative plates sitting on top of a base caliber. Real arabesque Geneva waves catch light in a way printed or stamped finishing does not.
Weight and case shape
A steel 44.25mm Speedmaster on a bracelet sits near 190 to 200 grams. Replica cases are usually a little lighter and thinner through the lugs, and the crown guards look soft and rounded under a loupe instead of machined with a defined edge.
What replicas get right, and what they never fix
The better replica Speedmasters nail the dial printing, the ceramic bezel insert, the sapphire crystal, and the overall size. The movement is where they stay wrong. A 7750 beats at 28,800 vph, has a rotor you can feel wobbling on the wrist, and has no Co-Axial escapement at all. Decorating the rotor and adding a fake bridge does not change the architecture underneath it.
A few smaller things worth knowing: orange anti-reflective coating is a myth on these references, "Swiss Made" appears on almost every counterfeit, and the text "Cal. 9900" never appears on a genuine dial. It lives on the movement.
Price reality check
Genuine 9900 Speedmasters trade somewhere in the $5,000 to $9,000 range depending on reference, box, papers, and condition. A listing asking a few hundred dollars for a "Cal. 9900" Speedmaster is not selling an Omega, and a listing priced like a real one but shipping from a random storefront is the worse outcome of the two. Buy the movement, not the dial text.