Quick Answer
A fake Cartier Tank Must 28mm usually fails on four points: case proportions, the crown cabochon, dial printing, and caseback engraving. A genuine Tank Must has polished bezel edges that meet the brushed case sides along a sharp line, a domed blue spinel cabochon set flush into the crown, dial text that stays crisp under 10x magnification, and deeply cut caseback engraving tied to a serial number Cartier can confirm. If any of those four checks looks soft, shallow, or off in color, treat the watch as not genuine until proven otherwise.
Prerequisites
- Digital calipers accurate to 0.01 mm
- A 10x jeweler loupe or a macro lens
- One desk lamp for raking side light
- A scale accurate to 0.1 g
- The watch, box, paperwork, and any service records
Step-by-Step Authentication Checks
- Measure the case across its widest point and from lug tip to lug tip. Cartier lists the small Tank Must near 29.5 mm by 22 mm, so sellers who round it down to 28 mm are using a loose label. A case that lands more than half a millimeter off on either axis is a warning sign.
- Weigh the watch head without the strap. A genuine steel Tank Must lands in a narrow weight band for its size, and counterfeit cases are frequently lighter because the steel is thinner.
- Inspect the crown cabochon under the loupe. Genuine spinel is domed, evenly saturated, and sits flush with the crown rim. Fakes use flat plastic or glass that sits proud, scratches, or reads purple instead of deep blue.
- Examine the dial text with the loupe. The Cartier signature should have clean serifs and even stroke weight, with no blurring, no double printing, and no ink pooling at the letter edges.
- Find the hidden Cartier signature inside the VII numeral. It is a deliberate design detail and counterfeit dials often omit it or place a clumsy blob where the numeral strokes should be.
- Check the minute track and the SWISS MADE marking at 6 o'clock. The track should be continuous, evenly spaced, and aligned with the printed indices, while SWISS MADE sits centered below it.
- Study the hands under side light. Genuine sword hands have straight, polished flanks and a sharp tip, while fake hands show rounded tips, uneven bluing, or scratches along the top surface.
- Read the caseback engraving at an angle. Genuine text is cut into the metal with crisp walls and consistent depth. Laser-etched fakes look shallow, grey, and slightly fuzzy at the edges.
- Record the serial number and reference number from the caseback, then verify both with a Cartier boutique or authorized service center before you commit to a purchase.
- Inspect the bracelet links and screws if the watch is on steel. Genuine links show tight tolerances with no side play, and screw heads sit flush without burrs or stripped slots.
- Have a qualified watchmaker open the caseback and photograph the movement. The Tank Must runs on a quartz caliber, and the module should carry correct Cartier markings plus a clean, machine-finished layout.
- Compare the box, warranty card, and booklets against known genuine examples. Card fonts, print quality, and serial placement on the paperwork should match the watch exactly.
Red Flags That Confirm a Fake
- Case dimensions that fall outside the published Cartier size by more than half a millimeter
- A cabochon that is flat, plastic, or the wrong shade of blue
- Blurry or doubled printing anywhere on the dial
- Shallow, grey, laser-etched caseback text instead of cut engraving
- A serial number that Cartier cannot match to the reference
- Paperwork with mismatched serials, thin card stock, or spelling errors
- Rounded hand tips and rough finishing on the bezel edges
When to Get Professional Verification
Self-inspection catches most counterfeits, but high-end fakes exist. Pay for a written authentication from a watchmaker who handles Cartier regularly, especially on any piece priced far below market, sold without papers, or shipped from a seller who refuses to open the caseback. A verification fee is cheap next to the cost of a misrepresented watch.