Short answer
There is no Cartier reference called 33665. Listings that use "replica ballon bleu 33665" are pointing at the Ballon Bleu de Cartier 36mm automatic, whose caseback is stamped 3366. Sellers pad the number, sometimes twice, and the extra digits stick. So the watch you are actually shopping for is the 36.6mm steel three-hander with a date at 3 o'clock and the blue cabochon set into the crown. Compare every replica against that model, not against the 33mm quartz or the 42mm.
Why the number matters more than the photos
Reference numbers keep you honest. A seller who can say "36mm automatic, 3366 case, 049 movement family" knows the product. A seller who only repeats the keyword is usually reselling whatever a factory shipped last season. Before anything else, ask for the case diameter and the movement name. The 36mm Ballon Bleu measures 36.6mm across, about 12mm thick, and wears closer to a 38mm round watch because the crown guard extends past the case edge. If a listing claims 36mm but the photos show a squat, thick case, you are probably looking at a smaller quartz case stuffed with a spacer.
The crown, the cabochon, and the one tell nobody hides
Start here, because it is where cheap replicas fall apart fastest. Genuine crown cabochons are a synthetic blue spinel, domed, deep blue, and set flush in a fluted crown that sits inside a rounded guard. On budget reps the stone looks like flat plastic, reads purple under indoor light, or sits crooked with glue visible at the edge. I also press the crown in and out. It should click once, firmly, with no grinding and no wobble. A crown that spins loosely is a crown that will fail in a year.
Dial and hands
The 36mm dial carries a fine guilloché pattern that radiates from the center in tight concentric rings. Genuine texture catches light and shifts as you tilt the watch. Replica dials often use a shallow stamped or printed texture that looks like a decal and stays flat under the same light. Then the printing: "Cartier" in the upper half, "Swiss Made" at the bottom, both crisp and thin. Look at the date window. It should be beveled at the edges, and the font should be a light serif, not a fat sans-serif blob. Last, the hands are blued steel swords. If they look painted rather than heat-blued, that is a marker of a lower tier build.
Caseback, bracelet, and weight
Engraving is a good honesty test. Clean edges, even depth, and a legible 3366 with a serial line means the factory cared. Sandblasted mush means it did not. On the bracelet, the links should articulate with a slight taper toward the clasp, and the butterfly clasp should snap shut with a solid click. Weigh it if you can. A steel 36mm on a full bracelet runs in the 120g to 130g range. Anything noticeably lighter is telling you the case is not the alloy it claims to be.
Movement expectations
Most quality 1:1 builds in this size use an A2824 or a Miyota 9015, sometimes with a decorated rotor meant to nod at the Cartier 049. Both are servicable and easy for a local watchmaker to regulate. Ask for a timegrapher photo before shipping. Anything inside plus or minus 10 seconds a day with amplitude above 250 is fine at this price point. What you should not accept is a listing that refuses to name the movement at all, or one that calls a 21-jewel Chinese clone a "Swiss ETA" without proof.
Quick checklist before you pay
- 10x macro shots of the dial printing and the crown cabochon
- A short video of the crown action and the second hand sweep
- Caseback photo with the reference and serial visible
- Movement name and a timegrapher reading
- Confirmed case diameter and thickness
- Clasp close-up and a stated weight
Expect to pay somewhere in the 250 to 450 dollar range for a well finished 36mm Ballon Bleu replica. Below that you are buying the silhouette and not much else. Above it, you should be getting a better movement, sharper engraving, and a cabochon that holds its color in daylight.