A 100-carat diamond hitting the auction block today in Manhattan could sell for as much as $25 million.

 

Sotheby's calls the classic emerald-cut diamond "perfect."

It was mined in southern Africa within the last 10 years and weighed over 200 carats before it was cut and polished.

Only five "perfect" diamonds over 100 carats have been sold at auction in the last 25 years.