Check out this rare 100-carat diamond up for auction

Sotheby is preparing to auction a 100-carat emerald-cut diamond in New York on April 21. The auction house says the diamond is incredibly rare and is expected to fetch as much as $25 million."This one is figured at $190,000 per carat at the low estimate," said Sotheby's chairman Lisa Hubbard. Hubbard says the high price tag is relevant in an investment market that can be seen as volatile."Diamonds, sapphires, rubies and emeralds have always had a certain amount of intrinsic value that make them, in people's minds, a good investment," she said. The diamond is part of a larger sale that includes other rare offerings including diamonds emeralds and sapphires.