The W4BB0024 is the diamond Ballon Bleu you'll find at Cartier today: a 36mm steel case with a bezel set with 54 brilliant-cut diamonds totaling 0.79 carats, a silvered guilloché dial with Roman numerals and blued sword-shaped hands, an automatic movement, and Cartier's interchangeable steel bracelet. It's the modern successor to one of the most loved diamond configurations Cartier has ever made – and like every diamond watch, it's really two watches waiting for the right strap. Below you'll find the exact strap size for the W4BB0024 and the options that suit it best.
Which Strap Size Fits the W4BB0024?
The Ballon Bleu W4BB0024 takes an 18mm strap. On our product pages, simply select the 18mm / 11mm option – that is the correct fit for the 36mm case.
One important note, because this reference is often mislabeled online: the W4BB0024 is the 36mm diamond model. If your diamond Ballon Bleu is the 33mm version (ref. W4BB0023, with 50 diamonds on the bezel), you'll need the 16mm / 8mm option instead. When in doubt, count on the case size, not the listing title.
As for the fit itself: the Ballon Bleu's fully rounded case and curved lugs mean an ordinary straight strap never sits properly 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 bracelet is no obstacle – the lugs accept a classic two-piece strap, and every Helvetus strap comes with its own buckle included, so nothing from the bracelet is needed.
A Quick Look at the W4BB0024
The Ballon Bleu has been Cartier's modern icon since 2007 – the convex case, the crown tucked beneath its arched guard, the blue cabochon floating like a balloon at three o'clock. The W4BB0024 crowns that silhouette with an unbroken ring of 54 diamonds, tracing the bezel in light above a softly glowing silvered guilloché dial. It's the configuration people picture when they think "diamond Cartier," now built on the current generation with its interchangeable bracelet.
Here's the truth about diamond watches, though: the diamonds are the constant – the strap is the setting. On the polished steel bracelet, the W4BB0024 is a full jewelry piece, spectacular for evenings and events. On leather, the same 54 diamonds become a refined accent on an elegant everyday watch. Nothing about the watch changes, and yet everything does.
Owners of this reference tend to be protective of it, and rightly so – the polished bracelet is where fine scratches show first. Rotating onto a strap for daily wear keeps the bracelet flawless for the occasions that deserve it, which is exactly how many owners of this reference wear it.
The Best Straps for the Cartier Ballon Bleu W4BB0024
Diamonds pair with a surprisingly small circle of colors – and they pair with them brilliantly. These are the strap choices that work best on this reference.
1. Blue Leather – Sapphires and Diamonds
Deep blue is what jewelers have set next to white diamonds for generations, and this watch was made for the pairing: blued sword hands, a blue cabochon in the crown, and now a rich blue strap to anchor them. The blue leather strap for the Cartier Ballon Bleu makes the 54 diamonds look even whiter by contrast and ties every signature detail of the W4BB0024 together. The most complete look this watch can wear.
2. White Leather – The Luminous One
The white leather strap takes the opposite route: instead of contrast, continuity. White extends the brilliance of the bezel and the light of the silvered dial down the wrist, turning the whole watch into one bright, seamless piece. A favorite among customers with diamond-set models, and stunning in daylight.
3. Black Crocodile – The Evening Standard
Diamonds over black crocodile is the oldest formula in fine jewelry, and the black crocodile strap executes it perfectly on the W4BB0024. Maximum contrast for the stones, a structured texture that matches their formality, and instant black-tie credibility. The strap for the nights this watch was bought for.
4. Brown Leather – Diamonds, Every Day
The brown leather strap is the unexpected one – and it works beautifully. Brown warms the steel, grounds the sparkle, and gives the 36mm case a relaxed, confident character that makes diamonds feel completely natural on an ordinary Tuesday. If you want to wear the W4BB0024 the most often, this is the strap that makes it effortless.
Prefer another shade? 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
Fifty-four diamonds shouldn't spend their life waiting for special occasions. With a strap or two in rotation, the W4BB0024 works as an everyday watch, an evening piece, and everything in between – while the bracelet stays as perfect as the day it left the boutique.
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. The diamonds are the constant – give your W4BB0024 a new setting.
