A Florida buyer snapped up a rare pink diamond Friday for $49.9 million in a record-setting auction. 

The 11.15-carat Williamson Pink Star diamond was sold at Sotheby’s Hong Kong. The auction house originally estimated its price at $21 million. 

A private collector from Boca Raton, Fla., purchased the precious gem, setting a world record for the highest price per carat for a diamond sold at auction, according to Sotheby’s. After taxes, the final price tag topped $57.7 million.

The final gavel for the rare jewel came after 20 minutes of frenzied bidding, the auction house said. Shortly after the sale was completed, the winning buyer changed the diamond’s name to the Rosenberg Williamson Pink Star, according to Sotheby’s. 

The Williamson Pink Star diamond was auctioned off at $49.9 million at Sotheby’s Hong Kong on Friday.

Photo: Associated Press

The gem’s original name pays homage to two other famous pink diamonds. The first is the 23.6-carat “Williamson” stone given to Britain’s Queen Elizabeth II in 1947 as a wedding present by John Williamson, a Canadian geologist who owned the mine in Tanzania where it was discovered. 

The second gem, the 59.6-carat Pink Star diamond, became the most expensive jewel ever sold at an auction when it fetched $71.2 million in April 2017, Sotheby’s said. 

Pink diamonds are a rare find among colored diamonds and tend to be the most expensive, according to Sotheby’s. 

Write to Ginger Adams Otis at Ginger.AdamsOtis@wsj.com