Sotheby's auctioning $25 million, 100-carat diamond

NEW YORK, March 29 (UPI) -- Sotheby's is set to auction an emerald-cut, 100.2-carat diamond worth an estimated $19 to $25 million on April 21 in New York City.

It is labeled as an internally flawless with no measurable nitrogen impurities. The diamond was originally more than 200 carats when it was sourced from a mine in southern Africa. The current owner spent more than a year working on the gem to present it in its current form.

"In terms of size and general shape, we have compared the diamond to a 9-volt battery," Gary Schuler, head of Sotheby's jewelry department in New York said according to Robb Report.

"What makes this stone so striking and rare is the combination of its impressive scale, the elegant shape, and the purity and crispness of the stone," Schuler said. "The limpid quality that you get out of a type IIa stone is exceptional in its own right, but at this scale and in this cut, it's extraordinary."

It is one of the rarest and largest stones that exist. It could join the list of five other diamonds measuring more than 100 carats to be have ever been sold at auction.

The Gemological Institute of America determined that the diamond is type lla and stated the diamond is color D.