$18 million pink diamond steals the show at Geneva auction

A pear-shaped, fancy vivid pink, VS2 clarity diamond, weighing 9.14 carats

A rare vivid pink diamond weighing over nine carats topped its estimate by fetching a cool 18 million Swiss francs ($18 million) at an auction in Geneva on Tuesday evening.

The jewel was snapped up by a private Asian investor and was the star of the sale hosted by British auction house Christie's, which collected in total just shy of 100 million francs for the 167 lots sold. Fifty lots - amounting to just less than a quarter of those offered – failed to find buyers.

The heady price tag, coming in at around 2 million francs per carat and racking up the second highest price ever paid for pink pear-shaped diamond at auction, reflects the ongoing strength in appetite for coloured gemstones.

Miroir de l’Amour: A pair of pear-shaped, D colour, flawless diamond earrings, weighing 52.55 cts and 50.47 carats, by Boehmer et Bassenge

The sale follows that of "The Oppenheimer Blue" diamond by Christie's in May 2016. That rectangular-cut, fancy vivid blue diamond weighing 14.62 carats, raked in a stratospheric $57.5 million and broke the existing record for the most expensive jewel ever sold at auction.

Louise Rowlingson, high jewellery specialist at Lorraine Schwartz's European flagship within Harrods, told CNBC that traditional diamond pricing doesn't apply to these hued gemstones.

"Coloured diamonds are exceptionally rare and valuable with red gemstones being the most difficult to find on the planet," Rowlingson said.

"Just like a high profile work by Picasso, market value for some of the most precious stones can be hard to estimate before it is revealed at auction."

But Rahul Kadakia, International Head of the Jewels Department at Christie's said that different customers were attracted by different stones.

"While we do see strong interest from Asian buyers in the field of coloured diamonds, the demand for colourless diamonds remains, with high prices achieved for the very best examples," Kadakia said.

The second-highest price achieved at the auction was for a pair of flawless diamond earrings, each weighing over 50 carats and together known as the Miroir de l'Amour (the Mirror of Love). Although the 17.6 million francs price coughed up by an anonymous buyer set the world auction record for a pair of earrings, it fell significantly short of the 20 million–30 million franc estimate.

Le Jardin d’Isabelle A D colour diamond and coloured diamond necklace by Boehmer et Bassenge

The fourth most expensive item was a diamond and coloured diamond necklace created by the same jewelers, Boehmer et Bassenge, and named Le Jardin d'Isabelle (Isabelle's Garden). Its anonymous winning bid of around 8 million francs came in at the low end of estimates.

And with prices for coloured diamonds continuing to rise over the past 30 years, Rowlingson says the appeal is clear.

"It's a dazzling investment that you can wear and enjoy day-to-day without detracting from any of its market value."

Furthermore, Kadakia believes the market for very exclusive jewels should withstand the turbulence which many see ahead for some global economic and financial markets.

"The market is totally immune to the macro environment surrounding it as pieces of high-quality and rarity with exceptional provenance always attract a lot of interest."

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