Short answer

A fake Clé de Cartier Large copies the case shape and the key crown. It does not copy the movement inside. The genuine Large runs Cartier caliber 1847 MC: automatic, 23 jewels, 28,800 vibrations per hour, 42-hour power reserve. Replicas run a Miyota 9015, a Seagull ST21, or a Chinese ETA 2824 clone. Cartier verifies a watch by serial number. No replica holds a serial in the Cartier database.

Genuine specs

  • Model line: Clé de Cartier, shown at SIHH in January 2015.
  • Large case: 40 mm diameter, about 11.7 mm thick.
  • Case metals: steel, 18k pink gold, 18k yellow gold, two-tone.
  • Movement: caliber 1847 MC, automatic, 23 jewels, 42-hour reserve.
  • Crystal: sapphire, front and back.
  • Crown: key shape with a cabochon set in the head.
  • Water resistance: 30 m (3 bar) on most steel references.
  • Dial: opaline or silvered, Roman numerals, date aperture.

Water resistance, cabochon stone, and dial color change by reference. Cartier lists each one in its online catalog. Unknown: no public Cartier serial lookup exists for buyers.

Replica specs

Most replicas sold as "large" measure 39 mm to 41 mm. Cases are plated brass or 316L steel. Glass is mineral on low tiers and sapphire on high tiers. Movement tiers:

  • Quartz: $30 to $80. The second hand ticks once per second.
  • Miyota 9015: Japanese automatic, 28,800 vph, 42-hour reserve. $200 to $350.
  • Seagull ST21 and 2824 clones: Chinese automatic, 28,800 vph. $150 to $400.

None of these movements match the 1847 MC rotor engraving or bridge layout.

Tells on a fake Clé de Cartier Large

  1. Case back engraving. Genuine text is cut deep and sharp. Copies show shallow laser marks and rough edges.
  2. Serial and reference. The eight-digit serial sits on the case back. Cartier staff can check it. A serial repeated across listings points to one batch.
  3. Crown action. The key crown on a genuine watch winds and sets with firm steps. Copies feel loose or grind.
  4. Dial print. Genuine CARTIER letters are crisp and level. Copies show thick paint and uneven spacing.
  5. Date window. The genuine aperture is cut with beveled edges and sits centered. Copies sit off-center.
  6. Bracelet screws. Genuine screws sit flush and take a 1.4 mm driver. Copies sit proud and strip.
  7. Weight. A steel Large on a bracelet feels heavy for its size. Plated copies run light.

Legal facts in the US

Import of counterfeit goods is illegal, including one watch for personal use. CBP can seize the item and destroy it. Trafficking in counterfeit goods carries up to 10 years in prison and a $2,000,000 fine for a first offense under 18 U.S.C. 2320. Cartier holds trademarks on the name, the dial design, and the crown shape.

Verification steps

  1. Get the serial and reference number, then call a Cartier boutique.
  2. Ask for a service receipt or a Cartier extract from the archives.
  3. Request photos of the case back and movement under bright light.
  4. Take the watch to a watchmaker who can open the case back. Movement ID takes two minutes.