Pink Diamond Expected to Fetch Over $60 Million Sotheby's is showing off a pink diamond that is expected to fetch more than $60 million at auction. The auction house was giving previews of what it calls the world's most valuable diamond ever to be offered at auction. Sotheby's said in a statement Wednesday that The Pink Star, a 59.60-carat oval cut pink diamond, would go up for auction on Nov. 13 in the historic five-star Beau-Rivage Hotel along Lake Geneva. David Bennett, chairman of Sotheby's Switzerland, says the vivid pink diamond is "of immense importance" because of its extraordinary size and exceptionally rich color that surpass all others known to exist in government, royal or private collections. He says it is "simply off any scale, and passes, I believe, into the ranks of the earth's greatest natural treasures."