Short answer

Reference 311.30.42.30.01.005 is the Omega Speedmaster Professional Moonwatch with a hesalite crystal, a solid steel caseback, and a hand-wound caliber 1861. Reference 311.30.42.30.01.006 is the sapphire version and runs caliber 1863. Counterfeits of both exist. Most fail on the movement, the crystal, the caseback engraving, or the price.

Match all eight digits

"311" is a prefix, not a model. Omega uses it across several Speedmaster lines, including the Moonwatch, the Moonphase, and the Dark Side of the Moon. Check the full reference on the caseback and on the warranty card.

Check the movement first

Caliber 1861 is hand-wound. It runs at 21,600 vibrations per hour, holds 18 jewels, and stores 48 hours of power reserve. Caliber 1863 carries the same specs on a movement with decorated bridges, visible through the sapphire caseback.

  • A quartz movement means the watch is fake. No Moonwatch 311 reference runs on a battery.
  • Chinese ST19 chronograph movements sit inside many counterfeits. The bridge shape differs and the engraving reads wrong.
  • An automatic rotor behind a solid caseback is wrong for a 1861.
  • Wind the crown. A real 1861 has firm, even resistance and a crisp chronograph start, stop, and reset.

Case, crystal, and dial

  • Case diameter is 42 mm. Lug width is 20 mm.
  • The hesalite crystal carries a small etched Omega symbol at the center. The sapphire version has the same mark.
  • Subdials sit at 3, 6, and 9. The 30-minute counter is at 3. The 12-hour counter is at 6. Running seconds are at 9.
  • The tachymeter bezel uses an aluminum insert with printed numerals and the word TACHYMETRE.
  • Hour markers and hands hold Super-LumiNova. Counterfeit dials show weak or missing lume.

Caseback text

The 311.30.42.30.01.005 caseback carries a seahorse medallion plus the lines "FLIGHT-QUALIFIED BY NASA FOR ALL MANNED SPACE MISSIONS" and "THE FIRST WATCH WORN ON THE MOON." Engraving on a counterfeit is shallow, uneven, or misspelled. Compare letter spacing against a photo of a real caseback.

Price and paperwork

Pre-owned 311 Moonwatches sell in the low thousands of US dollars. A listing at a few hundred dollars is not a real 1861 watch. Ask for the warranty card, the pictogram card, and the serial number. The number on the card should match the number on the watch.

Parts that are hard to fake

The 1861 movement finish, the crystal etch, the case profile, and the depth of the caseback engraving. A steel Moonwatch on the bracelet weighs close to 150 g. A light watch points to a fake case. Buy from a seller who accepts returns and who will photograph the movement and the serial.