PARIS (Reuters) - One of the last intact pieces of the French crown jewels that were sold off by the republican government in the 19th century, returned to France this week after being acquired by the Louvre museum.

"It's one of the most important pieces I've handled in all my career," said Francois Curiel, president of Christie's Europe, who negotiated the sale.

The diamond bow brooch, made up of 2,634 diamonds was created by the Parisian jeweler Francois Kramer for the Empress Eugenie, wife of Napoleon III, in 1855.

In 1887, after the fall of the Second Empire, it was sold at auction by order of the government of the Third Republic.

It was bought for Caroline Astor, queen of New York Society in the so-called "Gilded Age" before World War One, and remained in the Astor family for more than a century.

Initially put up for auction in New York earlier this month, the sale was cancelled at the last minute but the Louvre negotiated a private sale through the auctioneers and it was eventually secured for 6.7 million euros ($10.68 million).

"It's more than a commercial transaction. It's bringing a piece of heritage back to France," he said.