Answer first: 830107 is a caseback stamp you find on Must de Cartier Tank quartz watches from the late 1970s into the 1980s, not on a modern Tank Solo or Tank Louis. So a replica sold as a "Tank 830107" is a copy of a small, gold-plated, battery-powered dress watch with a lacquered dial. Judge it against that watch, not against a current-production Cartier.
Where the number comes from
Cartier's vintage numbering is a mess. Different lines, different countries, different years, and the stamps do not follow one clean sequence. The 830107 number shows up on Must de Cartier Tanks with the plated silver case and the flat, glossy dial. If a seller tells you the number itself proves anything about origin, that is a red flag. It is a label, not a certificate.
Case size and metal
The original is small. Think roughly 23mm across and 30mm lug to lug, around 6mm thick, with short straight lugs and a squared-off profile. Vermeil is the period-correct metal: sterling silver base with heavy gold plating. Good replicas use brass with plating, and you can feel the difference in weight. A 23mm brass case feels almost hollow. If you want something that wears like the real thing, ask the seller for the actual weight and the plating thickness. Anything under about 2.5 microns will wear through at the lugs within a year of daily wear.
Dial details I check first
Roman numerals, railroad minute track, sword hands. On this reference the printing is thin and slightly raised, not heavy and flat. Bring a 10x loupe and look at the letterforms: the C in Cartier should have a clean, even stroke, and the numerals should sit on the same baseline without floating. On cheap fakes the VII and VIII get crowded and the minute track drifts inward at 6 o'clock. The word SWISS at the bottom is common on this era, sometimes with T SWISS MADE. Neither is wrong by itself.
Crown, crystal and caseback
- The crown should carry a blue cabochon that sits flush in a milled seat, not a plastic dot glued on top.
- Most examples of this reference use a flat crystal. Mineral is period-correct on many; sapphire is not automatically a fault, but do not pay a premium for it on a plated dress watch.
- Caseback screws should be evenly spaced and sit below the surface. Replicas often have one screw slightly proud of the back, which catches on skin and tells you the machining was rushed.
- Engraving depth matters more than font. Real stamps cut into the metal. Laser-etched fakes look grey and shallow under angled light.
Movement
The original ran a small Swiss quartz movement, and Cartier signed some of them. Most replicas run a generic Japanese or Chinese quartz. That is fine for the money, but ask two things: does it hack, and is there a serviceable battery hatch or do you have to pull the back every time? A quartz Tank that needs a full caseback removal for a battery change is a nuisance you will notice every two years.
What to pay
This is a plated quartz watch. A replica of it should not cost anywhere near a mechanical Tank. If a seller quotes four figures for a gold-plated quartz copy, walk. The sweet spot for a decent example with sharp dial printing and a properly seated cabochon sits well below that, and the savings come from the movement, not the visible parts.
Quick checklist
- Measure the case. Around 23mm wide, roughly 6mm thick.
- Weigh it. Plated silver or a dense alloy, not hollow brass.
- Loupe the dial print at 10x for baseline drift and thin strokes.
- Press the cabochon. It should not move.
- Flip it. Screws flush, engraving cut deep, not etched.
- Ask about plating thickness and movement before you pay.