It’s been a big week for diamond auctions. With industry leaders Sotheby’s and Christie’s holding back-to-back auctions in Geneva on Tuesday 17th and Wednesday 18th May, respectively, we knew there were going to be diamond fireworks – and both auctions delivered.

The “Unique Pink”, a remarkable 15.38ct pear shaped diamond was part of Sotheby’s “Magnificent Jewels and Noble Jewels” auction in Geneva this past week. Mined near Kimberley in South Africa, Sotheby’s described the gem as “supremely rare and exceptional”.

Officially the largest pear-shaped vivid pink diamond ever to be auctioned, the stone was graded by the GIA as a “Vivid” colour, the highest possible colour grade.

Pre-sale estimates of the diamond were between $28 – $38 million, and the “Unique Pink” was sold for $31.56million, making it the most expensive Fancy Vivid pink diamond ever to be sold.

The sale price works out to $2.05million per carat, significantly more than the $1.70million per carat reached by the 16.08ct “Sweet Josephine” oval pink diamond sold in December last year.

The incredible rarity of pink diamonds means that they are highly sought after and command a premium when they appear on the auction block.

Pricey as these pink diamonds may be, they are no match for blue diamonds at the moment, as evidence by the sale on Wednesday night of the “Oppenheimer Blue”, a remarkable 14.62ct emerald cut blue diamond.

According to Christie’s, the stones auctioneers, this was the largest and finest fancy vivid blue diamond ever to be auctioned, and pre-sale estimates for the diamond ran from $38-$45million.

Living up to the hype, the diamond, previously owned by Sir Philipp Oppenheimer, sold for $51.3million after 25 minutes of bidding. The sale price crushed both the pre-sale estimates for the diamond and made the “Oppenheimer Blue” the most expensive diamond ever to be sold, significantly beating the previous record of $48.4million achieved for the “Blue Moon of Josephine” in December last year.

Blue diamonds occur when the element Boron is incorporated into the crystal lattice during diamond growth, and it is estimated that only 10% of any blue diamonds ever recovered are greater than 1ct in size, making the Oppenheimer Blue a remarkable collectors item.

Images courtesy Sotheby’s & Christie’s