Short Answer

A replica Cartier Tank Must 2021 is worth the money only when it matches Cartier's published dimensions for the size you pick: 33.7 x 25.5 mm for the Large and 29.5 x 22 mm for the Small. The case should be steel, the crown cabochon should be a blue synthetic spinel, and the movement should be quartz. If a seller will not confirm case size and thickness with a photo of a caliper on the watch, the rest of the build is usually off as well.

Prerequisites

  • Reference photos of the genuine 2021 Tank Must in Large and Small, showing the front, back, and side profile.
  • Digital calipers, or a seller willing to photograph the case against a ruler.
  • A phone with macro mode or a 10x loupe for dial work.
  • Knowledge of your country's rules on counterfeit goods before you order.

How to Check a Replica Tank Must 2021

  1. Confirm the size name against the numbers. Ask for the exact case measurement. A Large listed at 34 mm or a Small listed at 31 mm is a different mold and will wear wrong on the wrist.
  2. Measure the case thickness. The genuine watch sits close to 6.6 mm. A replica that measures 8 mm or more sits tall on the wrist and will not slide under a shirt cuff the way the real one does.
  3. Inspect the crown and cabochon. The crown is a fluted steel bead set with a blue synthetic spinel. Fakes often use glass or dyed plastic that looks flat and dull at the edges. A spinel shows facet lines and shifts brightness as you tilt it.
  4. Read the dial printing under magnification. Roman numerals should be crisp and spaced with no ink bleed at the serifs. Set your reference photo next to the watch and compare where the signature sits relative to the numerals.
  5. Check the hands. Sword shaped, blued steel, cut to reach the minute track without crowding the numerals. Blued hands shift between blue and near black as light hits them. Painted hands stay one color.
  6. Turn the watch over. Look at engraving depth on the caseback and the position of the Swiss Made line at 6 o'clock. Genuine engraving is cut into the metal, so a fingernail catches the edge. Printed text feels smooth.
  7. Confirm there is no date window. The 2021 Tank Must is time only. Any date aperture, however small, means the case is not based on this reference.
  8. Work the strap and buckle. The leather should taper toward the buckle, and the folding clasp should snap shut with no side play. A loose clasp is the part that fails first.
  9. Time it for 24 hours. A decent quartz module holds within a few seconds per day. If it drifts by more than that, the movement is low grade regardless of what the listing claims.
  10. Treat water resistance as a claim, not a fact. Keep any replica away from swimming, showers, and dishwater even if the listing says 30 m.

Common Mistakes

  • Buying from photos with no measurement in the frame.
  • Reading "Swiss movement" as proof of a Cartier grade module. It is not.
  • Ignoring the cabochon. It is the fastest tell at arm's length.
  • Paying extra for a box and papers that carry no real provenance.

Legal Notes

Replicas are counterfeit goods. In the United States, Customs and Border Protection can seize and destroy them at import, and selling one as genuine is trademark infringement and fraud. Personal use carries less exposure than resale, but the risk sits with you. Never present a replica as a genuine Cartier, and never pair one with genuine packaging in a sale.