You can tell if someone is Gen Z or a millennial by checking which Cartier watch they have

• Millennials and members of Gen Z both love Cartier watches, but they prefer different styles.
• Millennials favor the Panthère, evoking the old-money aesthetic and '80s nostalgia.
• Gen Z, on the other hand, opts for the vintage yet unique Baignoire.

Want to know how old someone is? Just check the style of the Cartier watch on their wrist.

Generational trends have long existed, with different age groups favoring styles and brands that cater to them. But online, fashion preferences have become more like a battle between millennials and members of Gen Z.

For example, the older group loves skinny jeans and tight leggings, while Gen Z opts for baggy, low-rise pants in fun prints and "hot girl errand fits."

And while both generations share an appreciation for Cartier craftsmanship, their ideal watches differ.

"There's a joke that millennials love the Cartier Panthère, and Gen Z loves Cartier Baignoires right now," Trang Trinh, a watch aficionado who runs the TikTok account Girls O'Clock, told Business Insider.

Going back in time

As Sotheby's said in an Instagram post, Cartier unofficially created the Baignoire watch in 1912 when it transformed a traditional, round clock into an oval shape.

The design officially launched in 1957, according to the art corporation, and had famous fans like Charlie Chaplin in its early days. The actor once gifted one to his wife.

The Panthère watch, on the other hand, is slightly more modern.

The square-shaped piece hit the market in 1983, as Harper's Bazaar reported, and was named after the graceful movements of panthers.

The publication said the accessory — meant to be worn functionally and as jewelry — instantly became popular with famous men like Keith Richards and Pierce Brosnan.

Millennials vs. Gen Z: Cartier edition

So, why do millennials love the Panthère style? And what makes the Baignoire stand out to Gen Z watch fans?

As Trinh pointed out to BI, they're "entirely different shapes" that appeal to two very different groups of people — namely, female watch collectors.

The Panthère, for example, is chic, reminiscent of the old-money aesthetic, and hearkens back to the '80s — both when the piece launched and when many millennials were born.

"The Panthère is more reminiscent of jewelry," Trinh said. "It's a rounded, square shape with these smaller, kind of rice-bead links that integrate beautifully. It's delicate, and the bracelet is really, really beautiful."

The Baignoire, on the other hand, is vintage but trendy, which Gen Z loves.

"The Baignoire is a bit more about its geometry than its jewelry-like quality," Trinh said. "It's got this simple oval shape with a curved bracelet."

That geometric shape gives the piece a fashion-forward edge and helps it stand out on the wrist.

"Gen Z is really looking for individuality in how they express themselves," she added.

But ultimately, you'll have to decide which Cartier watch is right for you.

If you want to keep things simple, maybe follow the trends of your generation. You can't go wrong there.

Or, you could follow your budget. Panthère watches retail for prices between $3,300 and $134,000, and Baignoires cost between $6,900 and $102,000.