The short answer
If a listing says "replica Speedmaster Master Chronometer 323," you are looking at a fake Omega Speedmaster wrapped in marketing language. Omega has never made a caliber numbered 323, and no Speedmaster reference carries that number. In practice the 323 is a factory batch code, a seller SKU, or shorthand for whatever clone movement sits inside the case. "Master Chronometer" describes a real Omega certification standard, but on a replica listing those words are copy, not proof of anything. So read the whole string as a statement of intent, then judge the actual watch on four things: movement, case dimensions, dial layout, and crystal profile.
What Master Chronometer actually certifies
On a genuine Omega, Master Chronometer means the finished watch, not just the movement, passed eight tests run by METAS, the Swiss Federal Institute of Metrology. Those tests include exposure to a 15,000 gauss magnetic field and a daily rate tolerance of 0 to +5 seconds. That is a watch-level certification with a serialized card tied to a specific case number.
A replica cannot hold that certification. Anyone selling you a fake with a "METAS certificate" is selling you a printed card. The useful takeaway is narrower: the standard tells you what the real Speedmaster family is built to, which is why factories bother copying the dial text at all.
Know which Speedmaster you are copying
The Moonwatch Professional is 42mm with 20mm lugs, a hand-wound movement in the current generation, and no date. Subdials sit at 3, 6, and 9, with running seconds at 9. The Speedmaster '57 is smaller at 40.5mm and uses an automatic Master Chronometer movement. The Speedmaster 38 line is smaller still.
This matters because the "323" label usually tells you nothing about which of these you are getting. Sellers mix references freely. Ask for the case diameter in millimeters, the lug width, and whether there is a date window. If the answers do not match a real Speedmaster layout, the watch will look off on the wrist even to people who do not know watches.
Movement: the part that decides everything
Hand-wound chronograph clones
The closest feel to a Moonwatch comes from a hand-wound column wheel chronograph, typically a Seagull ST19 family movement. It winds smoothly, the pushers have a light mechanical snap, and the beat rate is 21,600 vph. The tradeoff is a shorter power reserve and less shock tolerance than a modern automatic.
Automatic chronograph movements
Many Speedmaster-style fakes use a Valjoux 7750 derivative running at 28,800 vph. It is reliable and easy to service, but the subdial spacing and date position often sit wrong compared with the genuine dial, and the rotor makes a noticeable wobble on the wrist.
Clone co-axial movements
The top tier tries to copy the modern co-axial architecture. These can look convincing through a display back, but parts support is thin. If something breaks, the movement usually gets swapped rather than repaired.
Checks worth doing before you pay
- Start the chronograph and let it run a full minute. The sweep hand should return to zero on the first press, every time.
- Look at the subdial hands at rest. On a clean build, all of them point straight up at 12.
- Check the tachymeter bezel. Letter spacing on cheap reps is uneven, and the font looks thin.
- Confirm the crystal shape. A domed hesalite-style crystal and a flat sapphire crystal give the watch a completely different look from the side.
- Ask whether the pushers are screw-down. The Moonwatch pushers are not, so screw-down pushers on a Moonwatch copy are a giveaway.
- Request QC photos of the actual unit, taken with the chronograph running, not catalog renders.
Water resistance and daily wear
The real Moonwatch is rated to 50 meters. Treat any replica as splash resistant at best. A gasket that has never been pressure tested is a gasket you should not trust in a pool. If you swim, take it off. The same goes for steam and hot showers, which dry out seals faster than cold water does.
Questions to send a wholesaler
- Which movement is inside, and what is its beat rate?
- What is the exact case diameter and lug width?
- Is the crystal domed acrylic-style or flat sapphire?
- Which dial variant, and does it have a date?
- Can I see photos of the movement through a display back?
- Are spare links and a spare spring bar included?
Red flags
"Swiss made" printed on a watch at a casual price is a lie, since Swiss movement assembly is expensive. A claim of genuine METAS certification on a fake is a bigger one. So is "1:1 super clone" with no movement name anywhere in the listing. Ambiguous sizing, no real photos, and stock photography lifted from Omega's own site all point the same direction.
Bottom line
The "323" in the keyword is not a specification. It is a shelf label. Judge the watch by whether the movement type matches the reference you want, whether the dimensions are correct, and whether the dial layout is honest. Get those three right and the number in the title stops mattering.