A $300,000 watch? Luxury. A $300,000 watch that doesn’t tell time — and that sells out? Pure genius.

According to several news reports flagged by my friends at Luxist, Swiss watchmaker Romain Jerome just launched the “Day&Night” watch. The watch won’t tell you what time it is. That’s so yesterday. But it does tell you whether it’s day or night — helpful, I guess, for billionaire types who can’t afford windows.

The Day&Night watch (Romain Jerome)

As the company’s Web site boasts: “With no display for the hours, minutes or seconds, the Day&Night offers a new way of measuring time, splitting the universe of time into two fundamentally opposing sections: day versus night.”

What’s most impressive about the Day&Night is its complexity, given its absolute uselessness. The watch features two tourbillons — devices that overcome the ill effects of earth’s gravity on a watch’s accuracy — connected by a differential mechanism. Instead of hands, the watch has a “contemplative tourbillon operation whereby the ‘Day’ tourbillon operates for 12 hours to symbolize working life, while the ‘Night’ tourbillon takes over afterward to represent an individual’s private time.”

Like other Romain Jerome watches, the watch is made in part with steel salvaged from the sunken Titanic, along with material from the shipyard where it was built. That sounds creepy to me, but maybe today’s buyers prefer morbid metals.

The company’s chief executive, Yvan Arpa, cited statistical studies to explain how the watch better reflects the time-philosophy of today’s wealthy.

“When you ask people what is the ultimate luxury, 80 percent answer ‘time’. Then when you look at other studies, 67 percent don’t look at their watch to tell what time it is,” he told Reuters.

He added that anyone can buy a watch that tells time — only a truly discerning customer can buy one that doesn’t.

And here’s the best part: The watch sold out within 48 hours of its launch.