The tiara was kept in the Italian House of Savoy royal dynasty for more than 150 years. It was bought by an Asian collector, Sotheby’s told AFP.
The diadem, containing 11 natural pearls and diamonds, dates from the second half of the 19th century.
The tiara can also be separated into two parts, allowing it to be worn as a necklace.
Keen to attract the interest of a new generation, Sotheby’s created an Instagram filter that allowed people to create a picture of themselves wearing the Savoy tiara in a sumptuous Italian palace.
More than 22,000 people took advantage.
“This tiara encapsulates all the pomp, power and presence associated with royal jewels and over the past couple of weeks,” said Benoit Repellin, head of magnificent jewels sales at Sotheby’s in Geneva.
“The price achieved today is testament not only to its exceptional craftsmanship and the quality of its materials which makes it a true work of art, but also to its historical and emotional resonance.”