Quick answer
A fake Clé de Cartier Large is a replica of Cartier's 40 mm key-crown dress watch. The word large describes case size only. It does not mean a chronograph, a wider dial layout, or an extra complication. A strong replica copies the curved case band, the key-shaped crown set into a cutout, the Roman numeral dial, and an automatic movement finished to look like Cartier's 1847 MC. A weak replica uses quartz, prints the numerals too thick, and shapes the crown like an ordinary round crown with a blue stone glued on top.
What "Large" Means in the Clé Line
Cartier builds the Clé de Cartier in three main sizes: 31 mm, 35 mm, and 40 mm. The 40 mm version is what sellers call large. Case thickness sits at about 11 mm, which keeps the profile flat under a shirt cuff. The mid-size 35 mm is the version most buyers with smaller wrists pick, and the 31 mm is the ladies' reference. If a listing says large but shows a 35 mm photo set, you are looking at a mismatched ad.
Specs to Confirm Before You Pay
- Case: 40 mm across, steel or gold-tone, polished bezel that curves into the lugs without a hard step.
- Crown: key shaped, recessed into the case band, with a synthetic blue spinel cabochon.
- Crystal: sapphire, flat with a slight dome, anti-reflective coating on the underside.
- Dial: Roman numerals, railway minute track, blued steel sword hands.
- Movement: automatic, sweeping seconds hand, 25 to 28,800 vibrations per hour.
- Caseback: solid or sapphire, with engraving that matches the reference number quoted.
- Strap: leather with a deployant clasp, or a steel bracelet with the correct link count.
How to Check a Fake Clé de Cartier Large
- Ask the seller for a caliper photo of the case. The reading should show 40 mm, not 38 or 42.
- Request a side profile shot of the crown. On the Clé, the key head sits inside a cutout and turns to wind the watch. A glued-on cap or a standard round crown is a fail.
- Ask for a video of the seconds hand. A smooth sweep means automatic. A tick once per second means quartz.
- Zoom on the dial print. The Cartier script should be thin and even. Thick, blurry, or loosely spaced letters point to a cheap dial.
- Study the Roman numerals. The Clé uses a serif font with sharp corners, and the VII sits upright rather than tilted.
- Compare the caseback text. Reference numbers, metal, and water resistance lines should be crisp and centered.
- Ask which factory built it and which movement is inside. Sellers who name both are easier to hold to a spec.
- Confirm the return window in writing before payment. Photos hide a lot, and a short return policy protects you.
Red Flags
- A quartz movement described as "Japanese automatic."
- One listing covering 40 mm and 35 mm with the same photo set.
- No movement photo or video, only stock images pulled from Cartier's site.
- Water resistance claims above 30 m on a case that was never pressure tested.
- A price far under the going rate for the factory name quoted.
What a Replica Cannot Do
No replica Clé de Cartier Large carries a genuine 1847 MC movement, and Cartier will not service or authenticate a replica. Gold-tone plating wears through at the crown and lugs with daily use, and the tone drifts away from real 18k gold over time. If resale value or brand service matters to you, a replica is the wrong purchase.
Fit and Wear Notes
The 40 mm case sits close to the wrist because the lugs curve downward and the crown does not protrude. On a 6.5 inch wrist the large size is the upper limit. Buyers below that tend to prefer the 35 mm mid-size for the same dial design. Strap swaps are simple on the large case, so third-party leather bands fit without adapters.