The Archduke Joseph diamond, a storied gemstone weighing more than 76 carats, is expected to fetch over USD$15 million when auctioned by Christie's in Geneva this November.
Christie's head of jewellery, Rahul Kadakia, told Today that the 76.02 carat dimaond so is so prodigious in size that it can be "hard to visual."
"It's about the size of a quail's egg, and completely pure and clear in color," said Kadakia.
The colossal gemstone derives its name from its original owner the Archduke Joseph August (1872 – 1962), who was a member of the royal House of Habsburg-Lorraine as well as the head of state of Hungary for a brief period.
It was excavated from the now-closed Golconda mine in India, which was the source of some of the world's most renowned and stunning gemstones including the Kohinoor, now part of the British Royal Collection, and the Regent, the centrepiece of the French Crown Jewels.
The diamond vanished for decades after eluding the notice of the Nazis during the Second World War, before reappearing in 1961 at a London auction.
The auction in Geneva this November will mark the second occasion that Christie's has vended the gem, first auctioning it for $6.5 million in the same city in 1993. The diamond has since been sold privately yet Christie's has refused to identify its present owner.