$55 million Blue Moon diamond headed to auction

A stunningly rare and large blue diamond will be the centerpiece of Sotheby's jewelry auction this fall, carrying a $55 million pre-sale estimate.

Known as the Blue Moon diamond, the 12.03 carat gem is considered the largest cushion-shaped fancy vivid blue diamond to ever appear on the auction block. The diamond is expected to sell for upwards of $55 million dollars.

David Bennett, worldwide chairman of Sotheby's international jewelry division, calls the diamond "magical" and sensational" stone of perfect color and purity.

"Blue for me is the most mysterious and magical of all diamond colors." said Bennett "This gem will now take its place among the most famous gems in the world."

Discovered last year at the Cullinan mine in South Africa, the gem originally weighed in at 29.93 carats before its transformation. The mine is renowned for its carrot shaped volcanic pipe and is located approximately 45 minutes outside of Pretoria.

Cullinan remains the world's main source for rare blue diamonds. After 18 years run by the DeBeers diamond conglomerate, it is currently controlled by a three way consortium: Petra Diamonds, Thembinkosi Mining Investments and Saudi-based investment company, Al Rajhi Holdings.

The Cullinan Diamond Mine is expected to produce one million carats per year over the next 20 to 40 years.

It has also generated 25 percent of the world's diamonds over 400 carats.

The cushion cut Blue Moon has been rated internally flawless by theGemological Institute of America, and is rated 'fancy vivid blue,' the GIA'S highest possible color grading for blue diamonds.

"While any diamond with natural blue coloration is a rare discovery," Bennett said, "some are so exceptional that they emerge only once in a lifetime. A blue moon. This diamond is one of those remarkable occurrences."

In 2013, Christie's sold a 101.73 carat flawless white diamond to Swatch Group's Harry Winston division for record-breaking $26.7 million dollars, or $262,830 per carat.

At the time,Rahul Kadakia, international head of Christie's jewelry, said "the "investor appetite continues to grow for the Earth's rarest objects of natural beauty."

The sale of the Blue Moon diamond takes place November 11, 2015 at Sotheby's Geneva in Switzerland.