Christie’s will be presenting the Wittelsbach diamond, an extremely rare 35.56 ct., historic 17th century fancy deep grayish-blue diamond, to the international market for the first time in almost 80 years.

The diamond is estimated to fetch $15 million, Reuters reports.

“Known as ‘Der Blaue Wittelsbacher’ since 1722, it is one of very few diamonds which can claim 17th century heritage, incredible rarity and exceptional beauty,” Christie’s said in a statement. Upon the engagement of the Infanta Margarita Teresa (1651-1673) to Leopold I of Austria (1640-1705), who later became Holy Roman Emperor, her father King Philip IV of Spain (1605-1665) selected, in 1664, the diamond as part of her dowry. Subsequently, it entered the Austrian and then the Bavarian Crown jewels. The diamond is offered for sale from a private collection, where it has been since 1964.

The diamond will go on sale Dec. 10 at as part of its Jewels: The London Sale auction, being held at the auction houses’ King Street location.

“The appearance of a large blue diamond, among the rarest of colors, with a history that can be traced back to the 17th Century and 300 years of royal connections will surely be a thrilling occasion for all collectors of exceedingly rare jewels and works of art,’’ said François Curiel, chairman of Christie’s Europe and International Head of Jewellery Gemological Certification.

The Wittelsbach diamond is accompanied by a certificate from the Gemological Institute of America dated Sept. 24, indicating that the diamond is fancy deep grayish-blue, VS2 clarity.

JCK