Quick answer
Cartier lists the Ballon Bleu de Cartier in sizes from 28mm to 44mm. There is no 24mm reference in that range. A watch sold as a replica Ballon Bleu 24mm measures 24mm across the case, which puts it below the smallest genuine size. A buyer who wants a 1:1 match to a real Cartier should compare against the 28mm quartz model instead. A buyer who wants a small wrist fit uses the 24mm copy.
Case and fit
- Case width: 24mm. Lug to lug: 30mm to 32mm.
- Thickness: 7mm to 8mm on quartz versions.
- Strap width at the lugs: 14mm to 16mm. Measure the lug gap before ordering a strap.
- Weight: 25g to 40g in steel on leather. Plated versions run heavier.
- Wrist range: 14cm to 17cm reads best at this size.
Movement
Cartier uses quartz in its small Ballon Bleu sizes. Copies follow the same path. A 24mm replica almost always runs a Swiss Ronda or a Japanese Miyota quartz cell, which lasts 3 to 5 years. Automatic versions at 24mm exist but are rare. A 24mm case leaves little room for a rotor and a date wheel. Ask the seller which calibre is inside. A quartz second hand ticks once per second. A mechanical second hand sweeps.
Dial and crown
Three details separate a close copy from a rough one:
- The crown guard. The blue cabochon sits under a curved steel arc that meets the case at a right angle. Rough copies leave a gap or solder the arc.
- The dial. Cartier 24mm and 28mm dials use guilloche with concentric rings and Roman numerals. Printed flat dials are the common shortcut.
- The glass. Cartier uses sapphire. Many copies use mineral glass, which scratches and does not shed water the same way.
Materials and water rating
Case steel is 316L in most copies. Gold tone comes from PVD plating at 1 to 3 microns, or gold fill at higher cost. Water resistance on a copy comes from gaskets, not from the brand. A 3 ATM rating covers splashes and rain. Do not swim. ISO 22810 sets the test standard for dive ratings. Most 24mm copies are not tested to it.
Price bands
Low tier: $40 to $90, mineral glass, base quartz, printed dial. Mid tier: $120 to $250, sapphire, Miyota or Ronda, better dial print. Top tier: $300 to $600, hand-finished case, sapphire with AR coating, closer crown guard. Prices move with plating thickness and strap material.
What photos cannot show
Lume, crown thread feel, and gasket quality. Weight is the other gap. A genuine 28mm steel Ballon Bleu on leather weighs about 34g. Ask for a scale photo.