Short answer
A replica Clé de Cartier 41 mm copies a watch Cartier launched in 2015. The case measures 41 mm across. The real watch runs a mechanical automatic movement with a key-shaped crown that winds and sets the time. Most replicas in this size run a quartz movement or a low-cost automatic. Case thickness, crown action, and dial printing are the three details that separate the price tiers.
The watch being copied
Cartier showed the Clé de Cartier at SIHH in January 2015. Clé is French for key. The crown is cut like the head of a key and turns the same way a key turns in a lock. Cartier fits the model with caliber 1847 MC, an automatic movement with about 42 hours of power reserve at 28,800 vibrations per hour. Cases come in steel and in pink gold. The dial is silvered with Roman numerals, blued steel sword hands, and a date aperture at 3 o'clock on most references. Check the reference number before you compare specs, because Cartier sells the Clé in several diameters and the details change between them.
What differs on a replica
- Case thickness. A quartz copy needs less room inside, so the case often sits 1 mm to 2 mm thinner than the original.
- Crown action. On the real watch the key-head crown pulls out and turns with a firm click. On low-tier copies the crown often feels loose or does not pull to a clear second position.
- Cabochon. Cartier sets a blue sapphire spinel in the crown. Copies use cut glass or dyed resin. Glass shows bubbles under a loupe.
- Dial printing. Roman numerals on the original are applied or printed with sharp edges. Copies show thick or filled-in lettering, and the minute track can sit off-center.
- Crystal. The original uses sapphire. Copies at the low end use mineral glass, which scratches and reflects a purple tint under some light.
- Case back. Engraving depth and font size are the fastest tells. Compare the serial format against photos of the same reference.
- Weight. A hollow case and thin bracelet links read light on a kitchen scale.
Checklist before you pay
- Ask for the case diameter and thickness in millimeters, measured with calipers.
- Ask which movement sits inside, quartz or automatic, and the model number of that movement.
- Request macro photos of the dial, the crown, and the case back.
- Confirm the crystal material in writing.
- Check the bracelet end links for gaps against the case.
- Ask about the return window and who pays return shipping.
Legal note for US buyers
US Customs and Border Protection can seize counterfeit watches in transit. Selling or importing counterfeit goods is illegal in the United States, and a personal-use claim does not protect a seller. Sellers who ship into the US carry that risk. Buyers should know it before they order.
What is not known
Factory names, movement suppliers, and production batches change without notice. No public list ties a given replica to a given factory. Judge each watch on the photos and the answers you get, not on a label.