The short answer
A fake Cartier Tank is any Tank that did not come out of a Cartier workshop. That one word covers a $40 quartz watch from a folding table and a $350 replica with a Swiss quartz movement, sapphire glass, and a properly domed blue cabochon. Quality lives in the details, not in the label, so judge the watch on its finishing. Here is what I check, in order.
The dial tells most of the story
The Tank dial is almost empty space, and that makes every printing mistake visible. On a real Tank the Roman numerals are crisp and evenly weighted, the minute track is a thin chemin de fer printed in a consistent tone, and "Swiss Made" sits in small caps flanking the VI. Blurry numerals, a thick or uneven minute track, and a washed out logotype are the first things I look at. The Cartier signature should stay sharp under a loupe, not fill in as a blob.
One more dial detail separates the tiers. The quartz Tank Must and Tank Solo, the models most people are searching for, have no seconds hand. Not a subdial, not a central hand. If a listing shows small seconds at six or a third hand sweeping around, you are looking at a build that copied the shape and skipped the watch. Some automatic Tank references do carry a date, so match the reference number to the dial layout before you call a date window wrong.
Cartier's hidden signature is worth knowing about. On the Tank Louis Cartier the word "Cartier" is drawn into the stroke of the VII, so it reads as part of the numeral at a glance. Cheap copies either skip it or carve in a version far too wide to pass.
Crown and cabochon
The blue cabochon is where most fakes fall apart. On a genuine Cartier it is a smooth domed stone, evenly colored, seated flush in a fluted crown. On budget copies you get plastic or glass that looks flat, cloudy, or too dark, often sitting proud of the crown or spinning loose. Run a fingernail over the join. If you feel a lip, that is a bad sign.
Case, finishes, and caseback
The Tank case is a rectangle with two vertical brancards, and the proportions have to be right. The Tank Must small measures 29.5 by 22 mm, the large 33.7 by 25.5 mm, and the brancards should run straight, not bowed. Look at where polished meets brushed. On a good case the transition is a clean line with a slight bevel. On a cheap one the polisher rounded the edge and the reflections smear.
Flip it over. Engravings should be deep and clean, with a legible reference number, the model name, and a water resistance figure that matches spec. Shallow, laser etched, or misspelled markings give it away.
Strap and hardware
Real Tanks ship on alligator or calfskin with a signed buckle or folding clasp. Most sub-$100 copies arrive on embossed leather with a blank buckle and stitching that wanders. Swap the strap and the watch can look fine. Leave it on and it drags the whole thing down.
Movement is the honest part
Quartz is correct for the Tank Must and Tank Solo. Mechanical is correct for the Tank Louis Cartier, which uses a hand wound calibre, and for the automatic references. A high tier replica runs a Swiss or Japanese quartz module, or a decorated mechanical clone, and the hands set smoothly. A cheap one stutters, the crown feels gritty, and setting the time feels like turning a screw through sand.
Quick checklist
- Numerals and minute track are sharp, not fuzzy
- No seconds hand on quartz Must and Solo references
- Cabochon is domed, smooth, and set flush
- Brancards are straight and case proportions match spec
- Polished and brushed surfaces meet on a clean line
- Caseback engraving is deep and spelled correctly
- Strap has a signed buckle and even stitching
- Crown sets smoothly with no grinding
One last point worth saying out loud. Selling a replica as genuine Cartier is fraud, and that is a legal problem, not a style question. Buying a replica that is sold as a replica is a different transaction. Know which one you are in, and price accordingly.