The Pink Star Diamond, mined in Africa in 1999, is one of the largest jewels of its kind ever discovered.
Auction House Sotheby's says its quality surpasses all known vivid pink diamonds in any private or royal collection in the world.
The nearly 60 carat diamond is being auctioned in Switzerland next month, and is expected to sell for $60m.
Al Jazeera's Catherine Stancl reports from London.
Source: Al Jazeera