Quick answer: a replica Cartier Tank Must Solo passes only if the case measures 33.7 mm across by 25.5 mm, the profile stays close to 6.6 mm, and the crown carries a smooth blue spinel cabochon. Those three checks weed out most weak builds in under a minute.

One naming note before you start. Cartier retired the Tank Solo line in 2021 and folded the entry steel model into the Tank Must. Sellers still blend the two names, so "Tank Must Solo" means a Tank Must large or small model on a leather strap. Confirm which size you are inspecting.

Reference Specs to Memorize

Compare every watch against these numbers. Ask the seller for photos with calipers before you commit.

  • Large model: 33.7 mm x 25.5 mm case, 6.6 mm thick
  • Small model: 29.5 mm x 22 mm case, 6.6 mm thick
  • Movement: high autonomy quartz, about 8 years of battery life
  • Crystal: sapphire, flat with a slight edge bevel
  • Crown: fluted steel set with a blue spinel cabochon
  • Water resistance: 30 m
  • Strap: calfskin, or a steel bracelet with brushed links

Inspection Routine

  1. Measure the case with calipers at the widest point and across the lugs. Note any reading more than 0.3 mm off the reference.
  2. Measure case thickness at the crystal. Replica cases often run 7.2 mm or more, which changes how the watch sits.
  3. Angle the crown toward a light. The cabochon should be a smooth dome with no flat top and no cloudy color.
  4. Set the watch on a table and look along the case flanks. The brancards should be straight and parallel, not tapered.
  5. Pull the crown to the setting position and set the hands. Quartz movements tick once per second, so a smooth sweep is a mismatch.
  6. Inspect the dial under a loupe. Check that the CARTIER print has sharp edges and that the Roman numerals carry the correct serifs on the VII and the X.
  7. Turn the watch over. Engraving on the caseback should have depth and crisp edges, not a shallow laser etch.
  8. Wipe the crystal with a dry cloth. Sapphire clears fast and feels cool; mineral glass smears and holds warmth.
  9. Flex the strap. Good calfskin creases in fine lines and springs back; cheap leather stays stiff or cracks at the stitching.

Red Flags

  • Case thickness above 7 mm on a large model
  • Cabochon with a flat or faceted top
  • Swiss Made print sitting too high above the 6 o'clock marker
  • Buckle with soft, rounded edges instead of a defined Cartier shape
  • Case that feels hollow when you hold it between two fingers

Wrist and Strap Checks

Wear the watch for a full day before you keep it. The brancards should sit flat on the wrist, and the lug ends should not dig in. If the strap holes stretch within a week, budget for a replacement band. A 20 mm strap fits the large model; the small model takes 16 mm.

After You Keep It

Keep the watch away from hot water and steam. Gaskets on quartz cases age fast, and 30 m of water resistance covers splashes only. Have the battery replaced at a local shop every few years, and ask them to test the caseback seal at the same time. Store it on a flat surface so the strap keeps its curve.