The world's rarest diamonds available to buy

Weighing in at 18.96 carats, the Pink Legacy diamond will be the larges Fancy Vivid pink diamond ever offered at auction by Christie's when it comes up for sale on November 13, 2018 in Geneva. Graded Type IIa, a classification earned by less than 2% of diamonds, and boasting a colour and clarity typically only seen in diamonds weighing less than a carat, the Pink Legacy is descended from the Oppenheimer family and valued in the region of $30 to 50 million. The closest comparison seen at auction is the Pink Promise - a 14.93 carat Fancy Vivid pink diamond which sold at Christie's for $32.48 million in 2017.

This incredible necklace by Hong Kong-based jewellery artist Wallace Chan brings together an entire family of flawless diamonds weighing in at a total of 383.4 carats. 24 of the stones, including the 104 carat internally flawless centre stone, were cut from the Cullinan Heritage - a 507.55 carat rough diamond bought by retail jeweller Chow Tai Fook for $35.3 million in 2010.

The necklace itself represents 47,000 hours of work and features pink diamonds, green jadeite and white jade in ornate forms including a bat for good luck and butterflies for eternal love. As if that wasn't spectacular enough, the modular design of the necklace means it can be worn in 27 different ways making it the ultimate transformer jewel for your capsule collection.

At 407.48 carats this yellow-brown stone is one of the largest diamonds in existence and has an equally astonishing history to match. Discovered among a pile of a rubble by a young Congolese girl in 1989, the 890 carat rough stone was sold by her uncle to De Beers before passing into the hands of diamond dealers Donald Zale, Louis Glick and Marvin Samuels. After a brief spell on display at the Smithsonian, Samuels cut the stone into one large “triolette” centrepiece and 14 satellite stones.

Louis Glick offered the stone for auction at Christie’s in 1988 but the lot was withdrawn when it failed to reach the reserve price of $20 million – at least $8.5 million more than had ever been bid for a single stone. In 2002 Glick tried his luck on eBay but, at $15 million, the lot failed to gain any interest. Eventually it passed to Mouawad Jewellery who used the diamond as the centrepiece of its currently unsold L’Incomparable necklace which, with a price tag of $55 million, set a new world record as the world's most expensive necklace.

As if further proof was needed of Graff’s dealings with some of the world’s most exquisite diamonds, the third stone in our list to be in the company's possession is the Wittelsbach-Graff. An exceptionally rare 31.06 carat internally flawless deep blue stone, it originated in the Kollur mines of Andhara Pradesh and first belonged to King Philip IV of Spain for inclusion in his daughter’s dowry. It was bought by Laurence Graff in 2008 for £16.4 million and has been displayed at both The Smithsonian and Natural History Museum of New York.

The De Grisogono flawless diamond sold at auction in November 2017 for $33.7 million.

To celebrate its 25th anniversary, Geneva-based fine jewellery house De Grisogono is partnering with Christie's to offer the largest flawless D-colour diamond ever to come to auction. Weighing in at a huge 163.41 carats, the IIA type diamond was cut from a 404 carat rough discovered in the Lulo mine in Angola in February 2016 and took 11 months to cut and polish into the final dazzling emerald-cut stone. The diamond is currently set as the centrepiece of an asymmetric necklace featuring a further 18 diamonds and two rows of pear-cut emeralds which took 14 craftsmen around 1,700 hours to create. The necklace, whose estimated price is as-yet undisclosed, will be auctioned as the star lot of Christie's Magnificent Jewels sale in Geneva on November 14, 2017 while the Art of De Grisogono partnership will see a number of other important stones from the house be offered throughout Christie's Autumn season.