Quick answer

A fake Cartier Tank Must Black fails on a short list of checkpoints. The genuine watch is quartz with two hands and no seconds hand. Its crown carries a domed blue spinel cabochon. The dial print stays crisp under 10x magnification, and the caseback engraving is deep, even, and set in Cartier letterforms. A black dial hides print flaws in listing photos, so the black-lacquer Tank Must is one of the most faked Cartier references on the market. Inspect the watch in hand or on live video before you pay.

What you need

  • A 10x jeweler's loupe
  • A bright, diffused light source
  • Calipers or a steel ruler that reads in millimeters
  • A reference photo of the genuine model from Cartier's own product page
  • A watchmaker willing to open the caseback

Step-by-step: checking a Tank Must Black

  1. Set the watch on a flat surface under bright light and look at the dial. Count the hands. The Tank Must is a two-hand quartz watch. Any seconds hand means the watch is not a stock Tank Must.
  2. Watch the minute hand for 30 seconds. A quartz movement steps once per second. A smooth sweep tells you an automatic movement sits inside a case built for quartz.
  3. Hold the loupe over the word CARTIER at 12 o'clock. Genuine print has clean serifs and even spacing. Fakes show blur, uneven weight between letters, or a font that is too bold.
  4. Study the VII numeral. Cartier works a tiny secret signature into the VII on the references that carry it. On a fake the numeral is plain, or the hidden word is a blur.
  5. Check the XII and the VI. Both should be printed rather than applied, and both should sit square to the dial edge.
  6. Measure the case with calipers. Compare length, width, and thickness against the current spec on Cartier's product page. Fakes run thick, often by half a millimeter or more, and the brancards sit proud of the case.
  7. Look at the crown from the side. It should be fluted and should hold a domed blue spinel cabochon with deep color. Plastic, glass, or a flat blue disc is a fake.
  8. Turn the watch over. Genuine engraving is deep and even, with correct reference and serial placement. Fake engraving is shallow, laser-faint, or set in the wrong typeface.
  9. Tilt the dial toward a light. Black lacquer should read as one flat, deep field with no orange peel, no dust under the crystal, and no halo around the printed text.
  10. Ask a watchmaker to open the caseback. A Cartier quartz caliber fills the case with a clean module, a marked battery, and no glue. Sloppy soldering, tape, or a movement with the wrong jewel count confirms a fake.
  11. Cross-check the reference number, the box, and the papers against the model. A price well under the market for a current reference ends the inspection.

Checkpoints that end an inspection

  • Seconds hand present
  • Smooth sweeping second indication
  • Cabochon that is flat, cloudy, or plastic
  • Soft or misspelled dial print
  • Shallow caseback engraving
  • Case thickness above spec
  • Seller who refuses a watchmaker inspection

If you already own a suspect watch

  1. Stop wearing it and photograph the dial, crown, and caseback in daylight.
  2. Take it to a Cartier boutique or an authorized dealer for an authenticity check.
  3. Request a written service estimate, since that document records the movement and case numbers.
  4. Report a counterfeit sale to the platform and, for a shipment, to US Customs and Border Protection.

Before you buy

Buy the Tank Must Black from an authorized dealer, a boutique, or a seller who allows a pre-purchase watchmaker inspection. Counterfeit watches carry no warranty, no service parts, and no resale value, and customs agencies seize them at the border. A short inspection costs less than a fake.