The short answer
Start with the case. The real Omega Speedmaster Grey Side of the Moon (commonly listed as ref. 311.93.44.51.99.001) has a case cut from solid grey ceramic. Most replicas take a stainless steel case and coat it grey. That one difference drives almost everything else you can check: the weight, the way the metal reacts to a magnet, the sound when you tap it, and the kind of damage it takes. If the case is wrong, nothing else on the watch is worth arguing about.
What the genuine watch actually is
The Grey Side of the Moon came out in 2014 as the third member of Omega's ceramic Speedmaster family, after the black Dark Side and before the White Side. Omega spent years developing the grey ceramic, and it shows in the finish: a brushed, slightly warm grey that is not a paint or a coating.
- Case size around 44.25 mm, noticeably thick because of the movement and the domed sapphire.
- Grey ceramic bezel with the tachymeter scale applied in a warm gold tone (Omega's Sedna gold alloy), not printed.
- Sandblasted grey dial with a fine grain meant to echo lunar dust. Subdial at 3 o'clock combines the chronograph hours and minutes, running seconds sit at 9, and the date window is at 6.
- Hands in 18k white gold with lume, not painted steel.
- Calibre 9300 inside: automatic, co-axial escapement, silicon balance spring, roughly 60 hours of reserve, and a column wheel with a vertical clutch.
Where replicas fall down
Case and finish
Ceramic is lighter than steel and does not conduct the way metal does. Pick up a steel-based fake and it feels heavier and colder than the real thing at the same size. Tap it and you get a dull metallic ring instead of the flat, almost plastic knock of ceramic. A magnet is a rough hint only, since 316L stainless is barely magnetic anyway, but a coated steel case will show some pull while solid ceramic shows none.
Damage is the clearer test. Ceramic either survives or it shatters, and it never dents. A coated steel case chips at the edges and reveals grey steel underneath the grey coating, usually first at the lugs and the crown guards.
Bezel and dial
On the genuine bezel, the tachymeter numerals sit slightly proud and catch light like gold because they are gold. On fakes they are printed flat, often with a yellowish tone that reads as brass. Look at the numbers under an angle: printed scale disappears into the bezel surface, applied scale stands up.
Dial texture is the next gap. The real dial has a soft, even grain. Replicas tend to look either glossy or chalky, and the subdial rings are often too shallow. The date font is a common slip as well: genuine Omega uses a specific serif-less numeral shape, and copies routinely use a generic font with the wrong digit width.
Movement and pushers
The vertical clutch in the 9300 means the chronograph seconds hand starts cleanly, with no stutter or backward jump. Many fakes run modified 7750-based movements, and the chrono hand kicks or wobbles on start. Setting the date is another tell: on the genuine calibre the date sets through the crown, while a lot of 7750-derived copies use a recessed pusher or a second crown position that does not match.
Feel the pushers. A column wheel chronograph has a short, crisp, almost clicky travel. Cheaper movements feel spongy or long.
Caseback, numbers, and paperwork
The genuine watch has a sapphire display back. Look at the movement: Geneva stripes, an engraved rotor, blued screws, and finishing that is applied, not stamped into a plate. Copies either hide the movement behind a solid back or show a printed plate with shallow fake engraving.
Check the reference and serial engraving against the reference number on the warranty card and the pictogram card. Mismatched or reused numbers are one of the easiest things to catch, and a seller who will not photograph the engraving up close is telling you something.
Quick checklist
- Weigh it in your hand. Ceramic should not feel like steel.
- Tap the case. Metal rings, ceramic thuds.
- Angle the bezel to the light. Applied gold scale, not print.
- Start the chronograph. Clean start, no stutter.
- Set the date from the crown only.
- Read the caseback engraving and match the numbers.
- Look at the lugs for chips that expose grey metal.
What replicas get right
Being fair, modern copies nail the overall silhouette, the dial layout, and the strap. From arm's length on a wrist, a decent fake reads as a grey ceramic Speedmaster. The problems live in the details that only matter when the watch is in your hand, which is exactly why the case material is the first thing to check rather than the last.
Bottom line
The Grey Side of the Moon is a hard watch to copy well because the case is the whole point. Reproducing a ceramic case in volume is expensive, so the replica market mostly settles for coated steel and hopes nobody taps it. Buy the case first, the movement second, and the paperwork third, and you will catch most fakes before the price even becomes a question.