The Sun-Drop diamond of South Africa, a giant pear-shaped yellow gem weighing 110.3 carats, sold for more than US$10.9 million ($14.2 million) at auction yesterday, beating records for a jewel of its type.
Including commission, the unidentified telephone bidder paid almost US$12.4 million for the gem, putting it within the US$11 million to US$15 million range Sotheby’s had estimated before the sale.
“It’s a record for a yellow diamond at auction,” said David Bennett, the head of Sotheby’s jewellery division. He said it was the eighth most expensive diamond sold at auction.
After Sotheby’s sold a 24.78-carat fancy intense pink diamond for a record-breaking US$46 million last year, some had expected the auction’s headline piece to finish higher.
“When it gets to this price, there are only half a dozen people who can actually participate,” said Mourad Hatik, a Geneva jewel trader. “If they decide they already have a similar stone, then the price doesn’t go up.”
Still, exceptional gems such as the Sun-Drop would always attract bidders, he said
The Sun-Drop, which was found in South Africa last year, was put up for sale by New York-based company Cora International.
Gemologists had rated it as fancy, vivid yellow – the highest possible colour grading. Yellow diamonds are created when nitrogen impurities trapped within carbon molecules harden over millions of years.
Other lots at the US$70 million sale in Geneva’s Beau-Rivage hotel included a white cushion-shaped diamond weighing 38.88 carats that sold for almost US$7 million, including commission. A 12.01-carat emerald from Colombia’s Muzo mine sold for US$1.4 million and a blue diamond ring was snapped up for US$4.3 million.
However, several jewels – including a “peace dove” brooch, a blue diamond ring estimated at more than US$7.5 million, and a set of imperial jewels – failed to sell.
Nitrogen is by far the most common impurity found in gem diamonds and is responsible for the yellow and brown color in diamonds. Boron is responsible for the blue color.[11] Color in diamond has two additional sources: irradiation (usually by alpha particles), that causes the color in green diamonds; and plastic deformation of the diamond crystal lattice. Plastic deformation is the cause of color in some brown[26] and perhaps pink and red diamonds.[27] In order of rarity, yellow diamond is followed by brown, colorless, then by blue, green, black, pink, orange, purple, and red.[20] “Black”, or Carbonado, diamonds are not truly black, but rather contain numerous dark inclusions that give the gems their dark appearance. Colored diamonds contain impurities or structural defects that cause the coloration, while pure or nearly pure diamonds are transparent and colorless. Most diamond impurities replace a carbon atom in the crystal lattice, known as a carbon flaw. The most common impurity, nitrogen, causes a slight to intense yellow coloration depending upon the type and concentration of nitrogen present.[20] The Gemological Institute of America (GIA) classifies low saturation yellow and brown diamonds as diamonds in the normal color range, and applies a grading scale from “D” (colorless) to “Z” (light yellow). Diamonds of a different color, such as blue, are called fancy colored diamonds, and fall under a different grading scale.[20]
Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history.[5][6] The popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns.[7]