A fake Omega Speedmaster 311 almost always fails three checks: the inner caseback reference stamp, the finish and layout of the calibre 1861 movement, and the laser-etched Omega symbol at the center of the hesalite crystal. Genuine 311 references are 42 mm steel Moonwatches sold between roughly 2014 and 2021, and most copies are built on Seagull ST19 or Asian chronograph bases that cannot match those three details.

Which Speedmaster references carry the 311 prefix?

The 311 prefix belongs to the last steel Moonwatch generation built before the 2021 Co-Axial update. The two most copied versions are 311.30.42.30.01.005, with a hesalite crystal and a solid caseback, and 311.30.42.30.01.006, the sapphire sandwich with a display back.

Both share a 42 mm steel case, a 20 mm lug width, and a hand-wound movement. Other numbers in the 311.30.42.30 family differ only by strap, dial finish, or packaging.

How do you check the caseback and reference stamp?

The reference must be stamped inside the caseback and repeated on the movement bridge, and both must match the number printed on the pictograms card and the warranty card. Fakes often carry the correct outer text, "FLIGHT-QUALIFIED BY NASA FOR ALL MANNED SPACE MISSIONS" and "THE FIRST WATCH WORN ON THE MOON", because that wording is easy to copy. The inner stamp is where the shortcuts show.

The seahorse medallion on the solid 005 caseback should be crisp with sharp edges. Soft, shallow, or mushy relief is a warning sign.

What gives a fake 1861 movement away?

A genuine calibre 1861 is rhodium plated with Cotes de Geneve stripes, pink gold engraving, 18 jewels, and a Delrin brake on a cam system. Most replicas hide a Seagull ST19 or a decorated Asian chronograph, which shows a visible column wheel and a swan neck regulator the 1861 does not have.

Because the 005 has a solid back, the display back of the 006 is the better watch to inspect. Ask for a clear photo of the movement and compare the bridge shapes, not the labels.

Which dial and bezel details separate real from fake?

• The applied Omega logo and the printed "PROFESSIONAL" above the 12-hour subdial sit sharp, with no halo bleeding around the lettering.
• A 311 dial never reads "CO-AXIAL MASTER CHRONOMETER". That text belongs to the later 3861 generation.
• The bezel has a dot beside the 90, not above it. Dot over 90 belongs to 1960s and 1970s Speedmasters.
• Subdials sit at 3, 6, and 9, with running seconds at 9.

What does the hesalite crystal tell you?

The 311.30.42.30.01.005 uses a domed hesalite crystal with a small laser-etched Omega symbol at its center. Copies usually fit flat mineral glass or sapphire with the wrong curve and no etching. Tilt the watch under a light and look straight through the middle of the glass.

Do the case, pushers, and bracelet give anything away?

The case measures 42 mm across and about 13.7 mm thick, with pump pushers at 2 and 4 o'clock and a crown at 3. Genuine pushers click with a short, clean action, while copies feel spongy or travel too far. Bracelet end links should sit flush against the lugs with even brushing and a correctly stamped clasp code.

Why is the price the fastest test?

A used 311.30.42.30.01.005 usually trades between $4,000 and $6,000, and the sapphire sandwich sells for a few hundred more. A complete set offered well under $2,500, especially with box and papers, is a fake or a franken watch. Treat a low price as evidence, not as a bargain.

FAQ

Is every 311 reference a Moonwatch?

No. The 311 prefix covers several limited editions and strap variants, so confirm the full 11-digit number and match it to the exact catalog entry.

Do fake Speedmaster 311 watches keep time?

Many do, and some hold within a few seconds a day. Accuracy alone never proves authenticity, so check the movement layout and the reference stamps instead.

Where do you find the serial number?

The serial sits on the movement bridge, on the inner caseback, and on the paperwork. All three should agree, digit for digit.