Omega Speedmaster Moonwatch: Hesalite vs Sapphire (UK Buying Guide)

Almost every Speedmaster Moonwatch buyer reaches the same fork in the road: hesalite or sapphire? It sounds like a small detail, but the two versions look and feel different, and they are priced differently on the pre-owned market. Here is what really changes, what does not, and how to decide.

I buy and sell pre-owned Omega, Speedmaster included, so it is a question I am asked a lot.

The short answer

• Choose hesalite if you want the traditional Moonwatch: a domed acrylic crystal, a solid caseback and a slightly lower price. Scratches can usually be polished out.
• Choose sapphire if you want a crystal that resists scratches, and the display caseback that lets you see the movement.
• Choose a different Speedmaster if the 42mm size is too big for you. The 38mm Speedmaster is a very different, smaller watch (more on that below).

What stays the same

Both versions of the current Moonwatch Professional share the same case size and the same movement, so you are not choosing between a "good" and a "lesser" watch.

• Case: 42mm in steel, 20mm between the lugs, 47.5mm lug to lug.
• Movement: Omega calibre 3861, a manual-winding chronograph with a Co-Axial escapement and a power reserve of about 50 hours.
• Certification: Master Chronometer, approved by METAS (the Swiss Federal Institute of Metrology), and resistant to magnetic fields up to 15,000 gauss.
• Water resistance: 50m.
• Bezel: the classic "dot over 90" tachymeter bezel with an aluminium insert.

Omega introduced the 3861 in 2021 as the replacement for the long-running calibre 1861. The new movement added a stop-seconds (hacking) function and Master Chronometer certification.

Hesalite vs sapphire: the real differences

The thickness and weight figures come from Omega's own specifications: the hesalite is quoted for the steel-on-steel 310.30.42.50.01.001, and the sapphire figures are for the 310.30.42.50.04.001, which shares the sapphire-sandwich case.

The case for hesalite

Hesalite is the crystal material the original Moonwatch used, and it has a warmth and a domed look that a flat sapphire crystal does not. The dial seems to sit slightly deeper under the dome, and light plays across it differently.

It scratches more easily than sapphire, but that is only part of the story. Fine scratches can be buffed out with a polishing paste, and if the crystal is damaged beyond repair, replacing hesalite is generally a simpler and cheaper job than replacing sapphire. The solid caseback, with its engraved medallion, is part of the appeal for many buyers.

The case for sapphire

Sapphire is far harder to scratch, which matters if you wear the watch every day. The flat, anti-reflective crystal also gives a crisper, cleaner view of the dial, and the display caseback lets you enjoy the 3861 movement, which has a lovely finish.

It is not indestructible. A hard knock at the wrong angle can chip or crack sapphire, and then it needs replacing rather than polishing. But for most people wearing the watch normally, it will look new for longer.

On the pre-owned market, sapphire examples generally trade at a premium. Market data published by dealers puts it at roughly 10% to 20% over a comparable hesalite watch, though this varies with condition and papers.

Which one should you buy?

Think about how you will wear it rather than which spec sheet looks better.

• You want the classic Moonwatch experience: hesalite. It is the closest to the original, and a few light scratches become part of its character (or get polished away).
• You wear it daily, including at a desk or on a commute: sapphire. It keeps its clean look far longer.
• You like seeing the movement: sapphire, because it is the only one with the display caseback.
• You want the lowest entry price: hesalite, and if budget is tighter still, a pre-2021 calibre 1861 Moonwatch, which Omega has since discontinued. Check the reference carefully, because the 1861 and 3861 watches are easy to confuse in a listing.

Whichever you choose, condition and completeness matter more than the crystal. A hesalite with full papers and a clean case is a better buy than a tired sapphire without them.

The white-dial option in stock

Omega released the white-dial Moonwatch, reference 310.30.42.50.04.001, in March 2024. It is a sapphire-sandwich Speedmaster with a white lacquered step dial, applied logo and indices, and the same calibre 3861. It was the first regular-production steel Moonwatch with a white dial rather than a limited edition, which is why it created so much discussion.

If you like the idea of a Moonwatch that stands out from the usual black, this is the one. You can see the one I list here: Omega Speedmaster Moonwatch 310.30.42.50.04.001.

If 42mm is too big: the 38mm Speedmaster

Not everyone wants a 42mm chronograph. The Speedmaster 38 (reference 324.30.38.50.01.001) is a 38mm steel watch with a black dial, a date window at six o'clock and a self-winding calibre 3330. It has a column-wheel chronograph, a power reserve of about 52 hours and 100m water resistance. It is thicker than the Moonwatch at 14.7mm, but its 44.9mm lug-to-lug makes it a good fit for smaller wrists.

Omega's own website now lists this reference as no longer available, so pre-owned is often the practical route. I list one: Omega Speedmaster 324.30.38.50.01.001. For the full range, see the Speedmaster Moonwatch models, the other Speedmasters and the Omega page.

What to check on a pre-owned Speedmaster

1. Chronograph function. Start, stop and reset. The seconds hand must return exactly to zero, and the pushers should feel crisp.
2. Reference and year. The 3861 Moonwatch only exists from 2021. A watch described as a 3861 with older papers should raise questions.
3. Crystal. On hesalite, check for deep scratches or cracks around the edges. On sapphire, check for chips at the rim.
4. Bezel. The bezel should be evenly aged and the "dot over 90" should be correct for the model. Faded or replaced inserts are common.
5. Bracelet and clasp. Check for stretch, play in the end links and a clasp that closes firmly.
6. Caseback and movement. Make sure the caseback matches the model and the serial number matches the papers.
7. Service history and warranty. Omega says all its watches come with a 5-year warranty, so check the date on the card and whether any cover remains.

For a broader checklist that applies to any watch, see my 12-point guide to buying a pre-owned luxury watch.

Buy with confidence

I authenticate every watch before it is listed, describe condition conservatively and offer a 14-day return on purchases. You can browse all current stock, take a watch in part exchange, or ask me to source a specific reference.

Frequently asked questions

Is hesalite or sapphire better on the Speedmaster Moonwatch?

Neither is better overall. Hesalite is the traditional choice and is cheaper and easier to repair. Sapphire resists scratches and comes with a display caseback. Your choice depends on whether you value heritage or durability.

Is the Speedmaster hesalite crystal fragile?

It scratches more easily than sapphire, but light scratches can usually be polished out. A severe impact can crack it, although replacing hesalite is generally simpler and less costly than replacing sapphire.

What is the difference between the Speedmaster 3861 and 1861?

The 3861 replaced the 1861 in 2021. It adds a stop-seconds function and Master Chronometer certification from METAS, and uses a Co-Axial escapement and a silicon balance spring.

What size is the Omega Speedmaster Moonwatch?

The Moonwatch Professional is 42mm in diameter, 47.5mm lug to lug and about 13.2mm to 13.5mm thick, depending on the version. If that is too large, Omega also made a 38mm Speedmaster.