Short answer
Most fake Cartier Tank Must Medium watches fail on four points: case measurements, dial printing, the crown cabochon, and caseback engraving. Work through the checks below in order and you can separate a genuine Tank Must from a replica in about ten minutes with a loupe, calipers, and a phone showing reference photos of the exact model.
Before you start
- A 10x jeweler's loupe
- Digital calipers that read to 0.01 mm
- A desk lamp you can angle across the dial
- Product photos of the exact reference from the maker's own listing
- A gram scale accurate to 1 g
Tank Must cases come in several sizes, and sellers often mix up small, medium, and large. Measure the case instead of trusting the listing.
Step-by-step inspection
- Measure the case. Read the width across the horizontal midline and the lug-to-lug length, then compare both numbers with the published dimensions for that reference. A drift of more than about half a millimeter is a warning sign.
- Weigh the watch head. Steel replicas frequently use thinner cases and lighter alloys, so a head that comes in noticeably under the expected weight deserves a second look.
- Read the dial under magnification. Roman numerals should have sharp, even strokes with clean corners, and the minute track should run as a continuous line of uniform thickness.
- Check every printed element. Look at the brand signature and the "Swiss Made" line at six o'clock. Both should be crisp, centered, and free of ink spread or double printing.
- Turn the watch and study the hands. Sword hands should be flat, correctly proportioned, and finished in a consistent blue, with no burrs, scratches, or uneven polish on the edges.
- Inspect the crown. A genuine cabochon sits flush inside a polished crown, shows a deep even color, and does not wobble when you turn it. The crown should set the hands smoothly with no grinding.
- Angle the crystal toward the light. Reflections should stay clear and colorless, which points to sapphire. Fakes often use mineral glass that shows a faint haze at the edges.
- Examine the caseback engraving. Reference and serial numbers should be cut to an even depth, evenly spaced, and legible without squinting.
- Flex the strap and check the hardware. Stitching should run tight and straight along both edges, and the buckle pin and keeper should match the shape used on the real reference.
- Confirm the movement type. The Tank Must is a quartz watch with a solid caseback. A seller describing an automatic movement, or presenting a see-through back, is describing something else.
Fast red flags
- Roman numerals with rounded, joined, or uneven strokes
- A cabochon that looks like plastic, sits proud of the crown, or is the wrong shade of blue
- Blurry or shallow caseback engraving with inconsistent letter spacing
- Strap stitching that wanders, skips, or uses the wrong thread color
- A seller who will not send angled photos of the dial, crown, and caseback
What a visual check cannot prove
Print quality, weight, and finishing rule out most replicas, but none of them confirm a genuine parts set. If the money matters, take the watch to a Cartier boutique or a watchmaker certified to service Cartier, ask for a movement inspection, and request a service estimate in writing. A seller who resists that step has already answered the question.