Quick answer
A fake Cartier Tank Must reveals itself in four places: the secret signature inside the VII numeral, the printed text on the dial, the one-tick-per-second behavior of the quartz caliber 157, and the depth and alignment of the caseback engravings. The Tank Must arrived in 2021 as Cartier's steel entry Tank and replaced the Tank Solo. Because it runs on quartz and closes with a solid screwed caseback, a counterfeit has fewer places to hide than on a mechanical Cartier. You can complete the full inspection in about fifteen minutes with a loupe and a set of calipers.
Gather these before you inspect
- A 10x jeweler's loupe and a bright, diffused light source.
- Digital calipers accurate to 0.1 mm.
- The reference number for the exact size and metal you are viewing. Steel Tank Must references start with WSTA, gold with WGTA.
- Straight-on photos of the caseback, crown, dial, and buckle from the seller.
- The box, warranty card, and service paperwork, if any exist.
Authentication steps
- Loupe the VII numeral at 7 o'clock. On a genuine Tank Must the word Cartier is formed by the negative space cut inside the numeral. On a fake it is missing, misspelled, or printed on the surface instead of cut into the dial.
- Read the dial text at 12 and 6. Genuine printing has sharp serifs, consistent letter height, and even spacing, with Swiss Made centered below the VI. Fakes show thick, blurred, or drifting type, and Swiss Made is often off-center or absent.
- Inspect the hands. The Tank Must uses blued steel sword hands with straight flanks and clean tips that stop short of the numerals. Painted blue hands, tapered tips, or hands that reach the printed track point to a copy.
- Study the crown. A blue spinel or sapphire cabochon sits flush in the crown, with a dome that matches the crown profile. Plastic inserts, glue lines, or a cabochon that stands proud are wrong.
- Turn the watch over and read the caseback. Genuine engraving is deep, even, and centered, and it carries the Cartier name, the reference, the serial, Swiss Made, and the water resistance rating. Shallow dot-matrix or laser etching with soft edges is a strong tell.
- Measure the case with calipers. The Large model measures 33.7 mm by 25.5 mm at 6.6 mm thick, and the Small measures 29.5 mm by 22 mm. Deviations beyond a tenth of a millimeter mean a different case was used.
- Watch the seconds hand. The caliber 157 quartz steps once per second in a firm, even beat. A smooth sweep means a mechanical movement sits inside a watch that should be quartz, which no standard Tank Must is.
- Confirm the dial has no date window. No Tank Must reference carries a date. An aperture at 3 o'clock, or a cyclops over the crystal, disqualifies the watch on sight.
- Check the strap or bracelet. Cartier-signed buckles and clasps show crisp stamping and correct proportions, and the steel bracelet links are brushed and polished with tight, quiet articulation.
- Match the paperwork. The serial on the caseback must match the warranty card and the box label. Ask a Cartier boutique or an authorized dealer to verify the number before you pay.
- Have a watchmaker open the case last. The movement should carry Cartier 157 marking and Swiss quartz finishing, not a generic Ronda or Miyota module with a blank bridge.
Red flags that end the inspection
- Swiss Made printed inside the dial edge or split across the track.
- Roman numerals with the wrong serif shape or uneven stroke weight.
- A crown with no cabochon, or one that feels loose under a fingernail.
- Caseback screws that sit at uneven depths or show tool marks.
- An unbranded buckle or a strap with irregular stitching.
- A seller who will not photograph the serial or allow an inspection.
- A price far under the going rate for that reference in used condition.
High-grade replicas versus counterfeits
A high-grade replica can match the case dimensions, the dial layout, and the quartz beat, and it will still fail on engraving depth, font weight, cabochon color, and movement markings. Treat any watch sold as genuine that trips two or more checks as a counterfeit. Selling a replica as an authentic watch is fraud in the United States, and buying one for resale as genuine carries the same exposure. Buy replicas only from sellers who label them as replicas, and keep the receipt.
If the watch fails a check
Stop the transaction. Ask a qualified watchmaker for a written opinion on the movement and case, then request a refund from the seller in writing. If the seller refuses, dispute the payment through your card issuer or platform and report the listing to Cartier's brand protection team. Do not send a wire transfer for a Tank Must you have not inspected in person.