It's enormous, it's pink and it's flawless.

Unveiled in Hong Kong, the Pink Star, a 59.60-carat oval cut diamond is expected to fetch around $60 million U.S. dollars when it goes on auction in Geneva in November.

Sotheby's Asia chairperson, Patti Wong says the auction house is delighted to have the stone.

SOUNDBITE: Patti Wong, chairman of Sotheby's Asia, saying (English):

"This is the most valuable diamond ever to come on the auction market, being a vivid pink and internally flawless, it's simply out of this world and one of the greatest treasures from the earth."

Wong says colored diamonds are the rarest and Sotheby's expects lots of interest in this one.

SOUNDBITE: Patti Wong, chairman of Sotheby's Asia, saying (English):

"I think the appeal for colored diamonds has been increasing and especially around the world where it's seen not only as an alternative asset class, but something very, very rare and very, very collectable."

Mined in Africa in 1999 the Pink Star is twice as large as the most expensive jewel ever auctioned, which was also a pink diamond.