A one-of-a-kind Patek Philippe watch sold for $31 million at a charity auction in Geneva, making it the most expensive wristwatch ever auctioned.

The steel Patek Philippe Grandmaster Chime Ref. 6300A-010 smashed the previous record for an auctioned watch — the $17.7 million fetched in 2017 for the Rolex Daytona once owned by Paul Newman.

The Patek was sold as part of the Only Watch auction in Geneva held by Christie's to benefit research on Duchenne muscular dystrophy. For the sale, watchmakers including Patek, Audemars Piguet and F.P. Journe created and donated one-of-a-kind watches, which are coveted by top watch collectors around the world. The fact that the sale was for charity helped boost the bidding prices, according to the auctioneers.