Sterling Jewelers Blog
February 20th, 2014
Cora International, the luxury jeweler famous for cutting the largest pear-shaped vivid yellow diamond in the world, recently plunked down $25.6 million for the privilege of transforming an “exceptional” 29.6-carat vivid blue rough diamond into a faceted museum-quality masterpiece.


Only last month, Petra Diamonds Ltd. announced that it had unearthed an acorn-sized blue diamond at its legendary Cullinan mine in South Africa. Petra chief executive Johan Dippenaar called it “one of the most important blue diamonds ever recovered” and experts had underestimated that the stone would sell for upwards of $20 million.


Now Cora has the task of analyzing the structure of the angular rough diamond to determine its optimal final shape. The cutters will look to maximize the beauty, brilliance, clarity, color and weight. Very often, master cutters will sacrifice more than half of the stone’s carat weight in order to yield a perfect faceted diamond.

Cora is well equipped to take on the task at hand. The company has cut and sold some of the biggest diamonds in the world.


Its most famous to date is the 110-carat “Cora Sundrop Diamond,” a pear-shaped stone so impressive that it had been on display at the “Vault” in London’s Natural History Museum. The Vault is a special gallery reserved for the museum’s most rare and valuable treasures.


In 2011, the Sundrop was sold at Sotheby’s Geneva to an anonymous bidder for $10.9 million, a world-record price for a yellow diamond.

Blue diamonds get their color from trace amounts of boron impurities in their chemical makeup. Yellow diamonds occur with the presence of nitrogen.

Vivid blue diamonds are highly coveted and yield top prices at auction. Just last year, a fancy blue diamond weighing 5.30 carats broke the world record for price per carat when it fetched $9.5 million at Bonhams Fine Jewellery sale in London. The $1.8 million-per-carat bid eclipsed the previous record holder of $1.68 million per carat.