"A rare 27.54 carat step-cut Kashmir sapphire which exhibited a rich, saturated velvety blue colour achieved USD 5,984,474, a world auction record for a Kashmir sapphire," Sotheby's said in a statement.
The gem was purchased by a buyer from Asia, auctioneers said.
Previous record was set by a Kashmir sapphire weighing 28.18 carats when it sold for USD 5,093,000 at Sotheby's New York in April 2014.
Kashmir sapphires sport a rich lustrous blue colour often compared to that of a cornflower. In the 1880s a landslide in Kashmir, caused the legendary sapphires to be discovered. With a limited production, Kashmir sapphires make up a tiny percentage of the world's total sapphire supply.
The American Gemological Laboratories labels this stone a "Classic Kashmir," denoting that it not only exhibits the classic gemological features of the Kashmir region, but also represents the top quality of stones from the region.
Meanwhile, the sale of "Magnificent and Noble jewels" on November 12 was led by a 'Graff Ruby' from the collection of Dimitri Mavrommatis.
The 8.62 carat cushion-shaped gemstone soared above estimate and set a world auction record for a ruby at USD 8,600,410, as well as a record price per carat for a ruby at USD 997,727 when it sold to Laurence Graff, auctioneers said.
Another highlight of the sale was a natural pearl and diamond necklace formerly in the collection of Josephine de Beauharnais, Queen of Sweden and Norway and likely once the property of Josephine de Beauharnais the first wife of Napoleon Bonaparte and Empress of the French.
Comprising 111 pearls, the necklace achieved USD 3,426,669.
In addition to Beauharnais's necklace, the sale featured the 'English Rose' a diamond pendant, dating 1876, once the property of Queen Victoria of Great Britain, which made USD 71,367.
Commenting on the results, David Bennett, Chairman, Sotheby's Switzerland said,"The Graff Ruby mesmerises all who view it. It is truly a gem among gems, and quite simply the greatest ruby of its size I have ever seen."