The W2BB0038 is the yellow gold and steel Ballon Bleu in Cartier's current collection – a 36mm steel case with a fluted 18k yellow gold crown holding the famous blue cabochon, paired from the factory with an interchangeable two-tone band. Silvered guilloché dial, Roman numerals, blued sword-shaped hands, automatic movement. It's the most discreet way Cartier does two-tone today, and a leather strap suits it remarkably well. Here's the exact strap size for the W2BB0038 and the combinations that work best on this reference.
Which Strap Size Fits the W2BB0038?
The Ballon Bleu W2BB0038 takes an 18mm strap. On our product pages, simply select the 18mm / 11mm option – that is the correct fit for the 36mm case.
One thing every Ballon Bleu owner should know: the case is fully rounded and the lugs curve with it, so an ordinary straight strap never sits cleanly on this watch. Our straps for the Ballon Bleu are shaped for the case, following its curve so the strap sits flush at the lugs without gaps.
And the interchangeable two-tone band doesn't complicate anything. The lugs accept a classic two-piece strap, and every Helvetus strap comes with its own buckle included, so nothing from the original band is needed. Switching back for special occasions takes a minute.
A Quick Look at the W2BB0038
Since 2007, the Ballon Bleu has been one of the most recognizable silhouettes in watchmaking – the convex case, the crown tucked under its arched guard, the blue cabochon floating like a balloon at three o'clock. The W2BB0038 handles gold differently from most two-tone watches: instead of a gold bezel, Cartier placed the 18k yellow gold at the crown and in the links of the two-tone band, leaving the bezel in polished steel.
That makes this the subtle member of the two-tone family. On the wrist, the warmth comes from precise points rather than a full golden frame – and it's exactly why this reference transforms so beautifully on leather. Put it on a strap and the W2BB0038 becomes a refined steel Ballon Bleu with one golden secret: the fluted yellow gold crown wrapped around its blue cabochon. Quiet luxury, in the most literal sense.
There's a practical bonus, too. On this reference, the two-tone band is where most of the gold lives – and polished gold links are the first place fine scratches appear. Wearing the watch on a strap keeps that band safe for the moments it deserves, while daily life happens on leather.
The Best Straps for the Cartier Ballon Bleu W2BB0038
Yellow gold has been paired with the same handful of colors for over a century – because they work. These are the strap choices that suit this reference best.
1. Black Crocodile – The Dress Classic
Gold and black alligator is the oldest dress-watch recipe there is, and the black crocodile strap for the Cartier Ballon Bleu brings exactly that look to the W2BB0038. Against the black texture, the yellow gold crown becomes the single warm detail on the whole watch – impossible to miss, impossible to overdo. The strap to reach for when this watch needs to be at its most formal.
2. Brown Leather – The Warm Everyday
The brown leather strap softens the steel and echoes the warmth of the gold, giving the W2BB0038 a relaxed, heritage character that works seven days a week. Where black croc is the evening answer, brown is the one you'll wear the rest of the time – with everything from tailoring to a t-shirt.
3. Blue Leather – The Watch's Own Accents
Look at the crown: a blue cabochon set into yellow gold. Add the blued sword hands, and this watch has been quietly pairing blue with gold since the day it was made. The blue leather strap simply completes the thought – a rich, intentional contrast that gives the silvered dial noticeably more presence.
4. White Leather – The Fresh Contrast
The white leather strap brightens the entire watch, flowing tonally from the silvered guilloché dial while making the gold crown appear even warmer. A striking warm-weather and daytime option that turns the discreet two-tone into something genuinely eye-catching.
Want to see everything? The full strap collection for the Cartier Ballon Bleu also includes pink, red, and further options – all available in the same 18mm / 11mm fit for this reference.
Final Thoughts
The W2BB0038 was designed to move between worlds – gold enough for the boardroom, steel enough for every day. The strap is what lets you decide which world it lives in this week.
Helvetus is one of the leading names in aftermarket straps for luxury watches, and our Ballon Bleu straps are made specifically for this case shape rather than adapted to it. Every order ships free worldwide with no import costs, returns are easy, and more than 50,000 watch owners around the world trust our straps on their timepieces. Give the W2BB0038 a strap worthy of its crown – the rest of the watch will follow.
