Short answer
33660 is a replica catalog code, not a Cartier reference number. It maps to a counterfeit of the 33mm Ballon Bleu de Cartier in steel, the mid-size self-winding model that Cartier sells under references such as W6920071. If a listing uses "33660" and shows a 33mm round case with a blue cabochon crown, you are looking at a fake of that specific watch, not a limited edition or an obscure vintage piece.
Why the code matters
Seller catalogs number their stock so buyers can search the same item across sites. The number usually encodes the size and movement class the seller claims: 33mm case, automatic, steel, leather strap or steel bracelet. It says nothing about which workshop made it, what movement is inside, or whether the dial finishing is close to the real thing. Treat 33660 as a description, not a quality grade.
What the real 33mm Ballon Bleu has
- Steel case of 33mm across, roughly 9.9mm thick, with a curved profile that sits low on the wrist
- Sapphire cabochon set into the crown, which is shielded by a guard that grows out of the bezel in one continuous line
- Engine-turned flinque dial with printed Roman numerals and blued steel sword hands
- Self-winding calibre 076, built on a Sellita SW300 base, about 40 hours of power reserve
- Convex sapphire crystal with anti-reflective coating applied to the inside surface
- Hidden folding clasp on the bracelet, or a steel pin buckle on the alligator strap
- Water resistance rated to 30 meters, which is splash protection and nothing more
The tells I check first
Start at the crown. The cabochon on a real Ballon Bleu is a deep, slightly milky blue with a soft internal glow. Cheap fakes use resin or glass that reads either electric blue or washed out, and you can often see a ring of glue around the setting under a loupe. Next look at the crown guard. Cartier sweeps it out of the bezel so the transition has no seam. Copies tend to build it as a separate lump, thicker at the base, and the curve flattens where it meets the case.
Then tilt the watch toward a window. The flinque dial should shift and shimmer in a radiating pattern because the texture is cut into the metal before lacquer goes on. Many fakes stamp the pattern shallow or print it, so the surface stays flat and the light does not move across it.
Dial and hands
Roman numerals on the real dial are crisp with tight, even strokes, and the Cartier signature is a drawn script, not a font. On the printed numerals you can usually find a tiny hidden signature worked into one of the numerals, which is worth checking with a loupe. Fake dials oversoften the script, crowd the minute track, or space the numerals unevenly around the chapter ring.
Blued steel hands are heat treated, so they read deep navy with bright edges catching light. Painted hands look purple or flat, and the sword shape is often slightly too wide or too short at the tip.
Caseback, movement and weight
Engraving on a real caseback is laser cut with sharp walls and consistent depth. Copies sand cast or stamp it, so the edges round over and the serial looks shallow. Ask what beats inside. Genuine 33mm autos run the 076; replicas usually carry a Miyota 9015 or a Chinese clone of an ETA 2824, and the rotor engraving on those is faint with visible machining marks. Winding feel and rotor noise give it away fast.
What 33660 listings usually get wrong
- Cabochon color and setting depth
- Crown guard thickness and where it joins the bezel
- Dial texture that does not catch light
- Caseback fonts and engraving depth
- Crystal without inner anti-reflective coating, which shows a blue haze
- Bracelet links that use pins instead of screws
Before you buy
Ask for macro photos of the crown, the dial at an angle, and the caseback. Compare them side by side with official product shots of the 33mm steel model. If the seller cannot tell you the movement or refuses close-ups, that answers the question for you.