Sotheby's is displaying the startling Pink Star diamond in London before it's auctioned in Hong Kong next month.
The company says the gem should fetch more than $60 million when put on the block April 4, which would be a record for a pink diamond sold at auction.
It said Monday the 59.6-carat Pink Star is the largest flawless fancy pink diamond ever graded by the Gemological Institute of America.
Sotheby's jewelry division chief, David Bennett, said the gem's size and color "surpassed any known pink diamond recorded in history." It was mined in Africa in 1999.
The company sold the Blue Moon of Josephine diamond for $48.5 million in Geneva in 2015.