A rare pear-shaped vivid pink diamond fetched 30.8 million Swiss francs ($31.46 million) at auction on Tuesday, Sotheby's said, but several other large stones failed to reach the reserve prices set by the sellers.
The "Unique Pink", weighing 15.38 carats and mounted on a ring, sold to an Asian private collector bidding by telephone, the auction house said.
It was the star lot at the saleroom's semi-annual auction in Geneva, with a pre-sale estimate of $28 million-$38 million.
"The Unique Pink set a new world record for a fancy vivid pink diamond ... It's the highest price ever paid for a fancy vivid pink diamond," David Bennett, worldwide chairman of Sotheby's international jewellery division, told reporters.
The "Sweet Josephine", a fancy vivid pink diamond weighing 16.08 carats, held the previous record since selling for $28.5 million at rival Christie's in November, and still retains the price per carat record in the category.
Overall, the Sotheby's sale netted $175.2 million, "setting a new world record for any jewellery auction", Sotheby's said in a statement. It eclipsed $160 million set a year ago.
In all, 83.2 percent of the 488 lots on offer found new owners, but "The Emperor Ruby" was among those stranded, with a bid of 3.6 million francs.
"There were a few stones that were disappointing but overall the sale was a huge success," Bennett said.
A British collection of 29 jewels by French jeweller Cartier sold for $3.4 million, doubling its low estimate, he said.
A "new world record" was set for a jewel by the late Paris-based jeweller Alexandre Reza - a fancy intense blue diamond brooch surrounded with diamonds sold for $13.4 million, he said.
"We've made a great effort to put together a sale that we thought was suitable for this particular market which is strong for the right things," Bennett said. "It seems to have paid off."
Ehud Arye Laniado, chairman of New York-based Cora International LLC, which cut, polished and sold the pink diamond, told Reuters in the showroom: "It was the time to sell. It is quite a strong price.
"We think slowly the market is grouping together with people who do believe in strong prices for fancy coloured diamonds. It is a good sign because we see people who do believe in the resale value of those stones, like art," he added. "The trend will move to white diamonds."