It's not unusual for an auction house to call something unique. But Sotheby's latest diamond may be worth the $31.5 million it sold for Tuesday.
Dubbed "The Unique Pink," it's the "largest fancy vivid pink pear-shaped diamond" ever auctioned, Sotheby's says.
So how rare are we talking here? Sotheby's notes less than 0.002 percent of diamonds presented to the industry's top grading authority are pink.
And even fewer are over 15 carats.
Still, the diamond sold for less than the top estimate of $38 million.
And even that was far lower than the record for a pink diamond –– the "Graff Pink" 25-carat diamond sold in 2010 for $46.2 million.
As of Wednesday morning, the buyer of "The Unique Pink" hadn't been named.