Wednesday, 14 July 2021

“Exceptional” 39.34 carat blue diamond = $40.2m

Petra Diamonds (LON:PDL) 39.34 carat Type IIb gem recovered at its Cullinan mine in April was sold to De Beers and manufacturer Diacore for $40.2 million. Petra’s Blue Moon of Josephine diamond, cut from a 29.6-carat rough blue diamond, sold for $48.5 million in 2015. The price of $4 million per carat remains the world record. The Blue Moon of Josephine lost about 59% of its mass during cutting. If the same holds for the 39.34-carat blue diamond, the result would be a 16-plus-carat gem. At $4m per carat, the polished stone would be worth $64m.
Diamonds get their natural blue color from small amounts of boron trapped in the crystal carbon structure during its formation.