The largest and finest fancy vivid pink diamond ever offered at auction by Christie's it’s about to go under its hammer in Geneva, with experts expecting it to fetch a record price of between $30 million and $50 million.

The Pink Legacy was once owned by the Oppenheimer family, the former owners of De Beers.

The rectangular cut diamond, named Pink Legacy, was once part of the Oppenheimer collection, Christie’s said, referring to the family who built De Beers into the world’s No. 1 diamond producer.

It’s rated “vivid”, which is the highest rating for a diamond’s colour, as it displays the optimum hue of the stone. At 18.96 carats, is also the largest fancy vivid pink diamond Christie’s has ever offered and it would lead its Magnificent Jewels auction in November.

“To find a diamond of this size with this colour is pretty much unreal,” Rahul Kadakia, International Head of Jewellery at Christie’s said in a statement. “You may see this colour in a pink diamond of less than one carat. But this is almost 19 carats and it’s as pink as can be. It’s unbelievable.’

Scientists classify diamonds into two main “types” — Type I and Type II. In the latter, the diamond has a particularly rare, almost homogenous colour. “Pink diamonds fall under the rare Type IIa category of diamonds,” Kadakia said. “These are stones that have little if any trace of nitrogen, and make up less than two per cent of all gem diamonds. Type IIa stones are some of the most chemically pure diamonds often with exceptional transparency and brilliance.”

Christie’s to auction largest, finest pink diamond in its history

The Pink Legacy will be shown in Hong Kong, London and New York before being auctioned in Geneva on Nov. 13. (Image from video, courtesy...

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