LONDON, Dec 10, 2008 (AFP) - Defying the economic gloom, a diamond with a rich royal pedigree went under the hammer at Christie's auction house Wednesday for a record 16.4 million pounds (24.3 million dollars, 18.7 million euros).

Diamant Wittelsbach

The 17th century Wittelsbach diamond, weighing 35.56 carats, was estimated to be sold for some nine million pounds, but fetched the highest ever price for a diamond at auction in London.

Known as "Der Blaue Wittelsbacher," the gem was bought by King Philippe IV of Spain in 1664 and given in a dowry when his daughter Margaret Theresa married Leopold I of Austria.

It subsequently entered the Austrian and then Bavarian Crown jewels, although it has been in a private collection since 1964.

"It is a great honour and a lifetime dream to handle a museum-quality stone such as the Wittelsbach," said Francois Curiel, international head of jewellery at Christie's.

"The appearance of a large blue diamond, among the rarest of all colours, with a history that can be traced back to the 17th century and 300 years of royal connections (is) a thrilling occasion," he added.