Short answer

The Omega caliber 1861 is a hand-wound chronograph with 18 jewels that beats 18,000 times an hour. A real one ticks 5 times per second and holds 48 hours of power reserve. Watches sold as "1861" that carry a Seagull ST19 or a Valjoux 7750 inside run at other rates and show other jewel counts. Check the movement, the dial and the price before you pay.

What the caliber 1861 is

Omega built the 1861 on the Lemania 1873 base. It powered the Speedmaster Professional Moonwatch from 1996 until 2021. Specs:

  • Hand wind, single barrel
  • 18,000 vph, or 5 beats per second
  • 18 jewels
  • 48 hours of power reserve
  • Cam switching, not a column wheel
  • Rhodium-plated plates and bridges, silver-white in color
  • Engraved with the Omega symbol, "OMEGA", "1861" and "SWISS MADE"

Subdials sit at 3, 6 and 9. The 9 o'clock dial is running seconds, 3 o'clock counts 30 minutes, 6 o'clock counts 12 hours.

Movement checks

  1. Beat rate. Open the caseback and count. Five ticks per second means a real 1861. Six or eight ticks per second points to a Seagull ST19 at 21,600 vph or a 7750 at 28,800 vph.
  2. Jewels. The 1861 has 18. Chinese copies often carry 21 or 25.
  3. Finish. The 1861 is rhodium plated and reads silver-white. The older 861 shows a copper or gold tone. Many fakes plate the bridges yellow to copy the 861 look.
  4. Engraving. Real engraving cuts into the metal. Fakes print or acid etch the text, so letters look flat and shallow under a loupe.
  5. Spacer ring. Real watches use a metal ring between movement and case. Plastic rings show up in copies.

Case, dial and crystal

  • Hesalite Moonwatches built after 2001 have a small Omega symbol etched in the center of the crystal. It sits under the surface.
  • Dials before 1998 carry "T SWISS MADE T" at 6 o'clock with tritium lume. Later dials use Super-LumiNova and read "SWISS MADE".
  • The caseback has a seahorse medallion, "THE FIRST WATCH WORN ON THE MOON" and "FLIGHT QUALIFIED BY NASA FOR ALL MANNED SPACE MISSIONS". Fake stamping is soft and thin.
  • The pushers should feel crisp. A copy with a 7750 feels spongy and the reset can snap back hard.

Price and serial

One reference that used the 1861 is 311.30.42.30.01.005. In 2024 and 2025, used 1861 Moonwatches trade for about $4,000 to $6,000. New-old-stock examples run higher. A "new" watch at $150 to $400 is a copy. The movement serial is stamped on the bridge. An Omega service center can match it to factory records. I could not confirm a public database for that check.

Verification steps

  1. Ask the seller for a timed video of the running movement.
  2. Count beats for 10 seconds and multiply by 6.
  3. Compare engraving depth with a macro photo of a known original.
  4. Take the watch to an Omega service center or a watchmaker with Omega parts access.
  5. Walk away if the seller refuses to open the caseback.