Buyers will have a chance to bid for the biggest single-crystal diamond to hit the world market when a sparkling 179-ct. gem is auctioned in France later this month, Reuters reports.

Auctioneer Charles Peiffert said experts spent some 15 years chipping and polishing away at the black, pear-shaped gem, named “The Vulcan,” reportedly the largest single-crystal diamond to go on sale.

The size of an egg, it is likely to sell for up to $1.13 million when it goes under the hammer in Saint-Amand-Montrond in central France on June 27, Peiffert told Reuters on Thursday at a press showing in Paris.

“Its faceted pear-shaped form, its shine, its internal structure make it a unique and exceptional stone,” he reportedly said.

The stone, which boasts an interior of amber-colored crystallized graphite formations, originally weighed more than 380 cts. but was shaved down to half its size to show off its fine features.

“We had to hunt all over the world to find a craftsman skilled enough to whittle it down,” Peiffert told Reuters.

The diamond is mounted onto a platinum and white gold broach that would risk tearing all but the toughest of evening dresses.

Peiffert last year auctioned the world’s largest black multi-crystal diamond, which weighed over 498 carats, for $1.7 million.

The much smaller Vulcan would not fetch as much when it is auctioned on June 27, but is worth more money per carat, due to its perfect form, Peiffert reportedly said. “Single-crystal diamonds are much rarer, and its formations make this one particularly special,” he added.

JCK