Swiss luxury jewellery and watch company De Grisogono has bought the world’s most expensive rough diamond with the goal of turning it into a stone that "rivals the crown jewels”.  

Revealing the news at the 2016 Biennale des Antiquaires in Paris, de Grisogono said the purchase represents a “ground-breaking moment for the company in its journey to become one of the world’s leading high jewellery and watch brands”.  

Called The Constellation, the rough stone weighs 813 carats and is over 6 cm wide. 

It was discovered by Canada’s Lucara Diamond at its mine in Botswana in November 2015 and purchased for $63 million by Dubai-based Nemesis International earlier this year at a Sotheby’s private auction.

The Constellation naturally boasts the colour, clarity and carat weighting of an internationally and historically significant stone.  It is expected that the cutting process, due to be completed by the middle of 2017, may unveil one of the world’s largest certified flawless diamond, the jeweller says.

De Grisogono founder Fawaz Gruosi said: “I am thrilled to have the chance to work with such an incredible and important diamond as The Constellation. As a jeweller I am conscious of the extraordinary responsibility I have to the stone and to the team who have worked so hard to secure it. To be able to bring my creative skills to the cutting and setting process of such a stone is both an honour and a privilege and I cannot wait to realise my vision for it.” 

John Leitao, Chief Executive Officer of de Grisogono, said: “By purchasing The Constellation, de Grisogono has shown its commitment to bringing the most unique stones from around the world to our clients in exceptional and exclusive pieces.  We firmly believe that, despite a challenging market environment, people will continue to cherish and value those objects which are truly unique and special, such as this extraordinary piece of history. 

“Our position today has been enabled by the incredible vision and creative flair of Fawaz over the last 25 years, the support of our team and our clients and, most recently, by our mutually beneficial partnership with Nemesis.”

Leitao was also quoted by CNN as saying that the aim was to transform The Constellation into "a stone that rivals the crown jewels".

The Constellation represents the second major acquisition by de Grisogono this year after the purchase in May of a 404-carat rough diamond, also from Nemesis International.

De Grisogono also launched its new Folies collection of jewellery at the Biennale.

The new high jewellery collection of rings, earrings and necklaces marries the sparkle of diamonds with the vivid colours of rubies, emeralds, blue sapphires, black diamonds and onyx, and pays tribute to Gruosi’s unbridled creativity, daring choices and unconventional approach.

The Biennale, which opened yesterday and runs until September 18, has attracted 125 exhibitors from 14 different countries displaying antique furniture, art and collectables in the Grand Palais, one of the French capital’s most impressive monuments.