The "2370" in a fake Cartier Tank listing is not a model name. It is a four digit case code Cartier stamps on the back of certain Tank cases, and it sits there on genuine watches, on replicas, and on every listing that copied the number from a caseback photo. Matching that number proves nothing about authenticity.
What the 2370 stamp is
Turn a Cartier Tank over and the caseback carries several pieces of information in a small space: the brand name, "Swiss Made", a four digit case number, a longer serial number, a water resistance rating, the metal, and the movement type. The four digit number identifies a case design and a production batch, not an individual watch. That is why dozens of listings can say "Tank 2370" while describing watches that are years apart and made of different metals.
Reference coding varies across the Tank family. Tank Louis Cartier, Tank Française, Tank Américaine, Tank Solo, and the modern Tank Must each carry their own case codes. A stamp like 2370 belongs to that older shorthand, not to a catalog model name. Cartier's own materials and authorized dealers list models as Tank Française or Tank Must, not by four digit numbers.
Why the number is a weak authentication test
Replica makers copy caseback numbers straight from photographs, so a fake often carries a correct looking 2370 in a correct looking font. Anyone leaning on the number as their main check is inspecting the one detail counterfeiters nail. The stamp tells you which case a watch is imitating. Nothing more.
Where genuine and fake Tanks actually differ
- Crown cabochon. Genuine Tanks have a blue spinel cabochon set flush into a fluted crown. Fakes use glass or plastic, often cloudy, pinkish, or glued with a visible ring around the base.
- Dial printing. "Cartier" should sit crisp with even spacing, and a small "Swiss Made" at six o'clock. Fake dials show heavy serifs, drifting spacing, or "Swiss Made" placed too high.
- Secret signature. Many Tanks hide a tiny "Cartier" inside one of the numerals, on the VII in several references. It should be in the same ink as the rest of the dial and visible only at an angle. Fakes either skip it or print it bold enough to read straight on.
- Hands. Genuine blued steel hands are heat blued with a polished bevel that catches light. Replicas get painted flat blue.
- Engraving depth. Caseback text on a real Tank is etched to even depth with sharp edges. Fakes look shallow and rounded, with letter spacing that drifts.
- Movement. Quartz Tanks run a Cartier marked Swiss quartz caliber. Hand wound and automatic Tanks use Cartier calibers such as the 430 MC or an ETA base. Fakes ship with Ronda, Miyota, or unnamed Chinese movements.
- Weight and finish. Solid gold and steel cases have a density that plated brass and cheap alloys cannot hold up over years of wear.
What US buyers should know
Trafficking in counterfeit goods is a federal crime under 18 U.S.C. § 2320, and Customs and Border Protection seizes counterfeit shipments at the border. There is a narrow, discretionary personal use exception for a single item that is not meant for resale, and it does nothing for anyone buying quantity to flip. Cartier also refuses service on counterfeits, so a fake with a dead movement has no repair path and no resale market worth using.
A short pre-purchase checklist
Ask for a full caseback photo, the serial, and the papers. Confirm the serial on the card matches the case. Compare the crown, dial print, and hands against confirmed photos of the same reference. If a seller leans on "2370" as proof of anything, treat that as the warning sign it is. On a Tank, the number is the least useful detail on the watch.