“Blue diamonds like this are exceptionally rare, with only five over 10 carats ever coming up for auction, with none having more than 15 carats,” the auction house said.
De Beers Cullinan Blue will be auctioned in Hong Kong in April and is expected to fetch more than the Blue Moon or Josephine, a 12.03-carat blue diamond, which went under the hammer in 2015 for $48.4 million.