Short answer
There is no solid gold Tank Must in the current Cartier catalog, so a gold Tank Must replica copies either the 1970s Must de Cartier in vermeil or a steel Tank Must with a gold-tone case. Judge the replica on the gold layer, the case dimensions, and the movement. Those three decide whether it reads as a gold Cartier on the wrist or as a plated watch that wears through at the lugs within months.
Before you start
- Pick the reference you are matching: vintage Must de Cartier (vermeil, quartz) or the 2021 Tank Must (steel, quartz or SolarBeat).
- Know the correct case size: 23 x 30 mm for the classic vintage Must, 25.5 x 33.7 mm for the large modern Tank Must, 29.5 x 22 mm for the small.
- Have a jeweler's loupe, a digital scale, and a caliper on hand.
How to inspect one, step by step
- Weigh the watch head on a digital scale. Vermeil over sterling silver lands heavier than brass with plating, so a case that feels light is a sign the gold is a thin flash over base metal.
- Measure the case with a caliper and compare the numbers to the correct reference size. Replicas often run a millimeter or two wide, which throws off the brancards.
- Turn the watch over and look at the caseback edge where the gold meets the case sides. Plating wears first at sharp corners, so any dull yellow or grey showing through means the layer is thin.
- Read the engraving under a loupe. Genuine vermeil pieces are stamped for the silver content and the gold layer. Shallow, fuzzy, or missing stamps point to a cheap build.
- Study the brancards, the two vertical bars that frame the dial. They should run straight, sit proud of the dial, and hold an even polish with no ripples along the length.
- Check the dial print: the Cartier script, the Roman numerals, and the hidden Cartier word inside the VII. Edges should be crisp under magnification, not fuzzy or uneven in weight.
- Look at the crown. It must carry a blue synthetic spinel cabochon set in a smooth dome, flush with the crown, and the crown itself should be faceted, not a plain round knob.
- Run the movement. Set the hands through a full 12 hours and watch for stutter or a slack crown. Quartz is correct here. A mechanical movement in a Must is a mismatch.
- Flex the strap and check the buckle. Alligator-pattern leather with even stitching and a signed buckle matches the original. Stiff plastic-feel leather does not.
Gold layer types
Vermeil means sterling silver with gold plating. French rules call for 5 microns of gold, while US rules set the floor at 2.5 microns. Cheap replicas run 1 micron or less and wear to bare metal at the lugs and caseback within a season. Electroplating gives the warm yellow tone buyers want but scratches easily. PVD coating wears longer and keeps a sharper edge, but its color leans green-grey under daylight, which reads wrong next to real gold jewelry.
Red flags
- Case size off by more than 0.5 mm from the reference you asked for.
- A crown cabochon glued proud of the crown or set in too dark a blue.
- Print that bleeds, or a Roman numeral VIII with the wrong stroke weight.
- Caseback screws sunk shallow or with stripped slots.
- A seller who cannot name the gold thickness or the case metal.
What to expect at each price
Below roughly 120 USD you get brass with a thin flash plate, a printed dial, and a generic quartz module. Between 150 and 350 USD the better sellers use a steel or silver case, 3 to 5 microns of gold, a Swiss or Japanese quartz movement, and a sapphire crystal. Above that you are paying for tighter dial print, a signed crown, and a strap that matches the original grain. Ask for the case metal and the plating thickness in writing before you pay, and return anything that arrives lighter than the seller described.