OMEGA · Speedmaster Moonwatch Professional
OMEGA Speedmaster 310.30.42.50.01.001: specifications and what to check
The Hesalite Moonwatch. Same calibre and case as its sapphire sibling, a different crystal, and a different reference number — which is the only reliable way to tell which one you are being offered.
Reference 310.30.42.50.01.001 · specifications read from the manufacturer on 2026-09-23 · listed as current
Specifications
As published by OMEGA. A field the manufacturer does not state is left out rather than filled in.
- Case
- Steel, 42 mm
- Diameter
- 42 mm
- Thickness
- 13.54 mm
- Lug width
- 20 mm
- Lug to lug
- 47.5 mm
- Water resistance
- 5 bar (50 metres / 165 feet)
- Crystal
- Hesalite crystal with OMEGA logo in the centre
- Dial
- Black
- Bracelet
- Steel
- Clasp
- Foldover clasp with comfort setting
Movement
- Calibre
- Calibre OMEGA 3861
- Type
- Manual-winding chronograph movement with Co-Axial escapement
- Power reserve
- 50 hours
- Frequency
- 3 Hz
- Certification
- Master Chronometer, approved by METAS
- Notes
- Resistant to magnetic fields reaching 15,000 gauss. Free-sprung balance with silicon balance spring; rhodium-plated finish with bridges carrying straight Geneva waves. Total product weight approximately 134 g.
What to check before you buy
- Identify the crystal before anything else. Hesalite is a plastic: it scratches easily, polishes out with a cloth and compound, and carries a small OMEGA logo etched at its centre. A sapphire crystal on this case means you are looking at a different reference number.
- Do not treat scratches on a Hesalite crystal as damage in the way you would on sapphire. They are expected and largely removable, and pricing them as permanent faults misreads the material.
- Check the 3861 is what is fitted. The Moonwatch has used several calibres across its history, and the Master Chronometer 3861 is the current one — papers and caseback should agree.
- Confirm the pushers and crown operate cleanly through a full chronograph cycle: start, stop, reset to zero with all three hands returning precisely.
- Remember the rating is 50 metres. This is a chronograph with pump pushers, not a diver, and a buyer who assumes otherwise has been sold the wrong story.
The crystal is the reference
OMEGA sells this case and this movement with two different crystals, and the only dependable way to tell them apart is the reference number. This one, 310.30.42.50.01.001, is specified with a Hesalite crystal with the OMEGA logo in the centre.
That matters more than it sounds, because the two versions are described loosely and often interchangeably in listings. A seller who says "Moonwatch, 42mm, 3861" has told you almost nothing about which watch is in the box. Ask for the full reference, and check the crystal in the photographs.
Hesalite is not a defect
This is the most common mistake a dealer new to the reference makes when buying. Hesalite is an acrylic. It will be scratched on any watch that has been worn, and those scratches come out with polishing compound and a few minutes of work.
So a scuffed Hesalite crystal is not equivalent to a scuffed sapphire one. It is closer to a dirty dial than to a chipped bezel: cosmetic, expected, and cheaply reversible. Discounting hard for it is a way to buy well, and describing it as damage when you sell is a way to lose a sale you should have made.
Sapphire, by contrast, resists scratching and fails by chipping — which is the opposite inspection problem.
What the 3861 actually certifies
The movement is a manual-winding chronograph with a Co-Axial escapement, certified Master Chronometer and approved by METAS. OMEGA states resistance to magnetic fields reaching 15,000 gauss, a free-sprung balance with a silicon balance spring, and 50 hours of reserve at 3 Hz.
The magnetic-resistance figure is the one worth understanding commercially. This is a hand-wound chronograph that can sit next to a laptop, a phone or a magnetic clasp without consequence — something that was emphatically not true of the Speedmasters that preceded it.
Fifty metres, and a hand-wound movement
Two facts a buyer should hear before they buy rather than after.
50 metres is splash resistance. The pushers are pump-style and not screw-down, and this watch should not be treated as a swimmer.
Manual winding is a daily obligation, not a preference. Some buyers want exactly that. Others discover it a week in and want to return the watch, which is avoidable entirely by saying so at the point of sale.
Price references like this, faster
What a reference is worth at intake, what to check before you buy it, and where it sells best. Free guides for dealers.
Sources
Not affiliated with OMEGA. Specifications are read from the manufacturer's own published documentation on the date shown and may change; the manufacturer's current documentation governs.