Top security protects vault of priceless gems

Despite a previous raid alert, museum puts the rarest of stones on display

Curators at the Natural History Museum in London are to open a display of some of the world's most expensive gems and jewels - even though they had to close a similar exhibition two years ago when police warned that it was about to be raided by an armed gang.

The new, permanent exhibition, to be called The Vault, will feature some of the world's most famous emeralds, diamonds, rubies, and other gems, as well as some of the rarest meteorites to fall on the planet, including one piece that scientists have discovered came from Mars. Most of them are considered priceless.

However, the museum insisted the new exhibition has been designed to ensure maximum security, although it would not discuss what measures it had taken to deter raiders. 'We are confident that security has been taken care of and the gems and other items will be safe,' said a spokeswoman.

The museum's previous exhibition of jewels had focused only on diamonds and included the De Beers Millennium Star, the Blue Empress and the Ocean Dream, some of the world's biggest, flawless diamonds. More than 70,000 people visited the display. But on 22 November 2005 it was closed abruptly when Flying Squad detectives warned that a violent raid was about to take place. Police had become increasingly concerned about a group of Eastern European criminals who had been paying 'regular visits' to the museum. 'The only responsible course of action was to close the exhibition,' said director Michael Dixon.

However, the new exhibition differs from its predecessor because it contains a far wider range of rare gems and rocks, and includes several priceless jewels with romantic histories. The Devonshire Emerald, one of the world's largest and best known uncut emeralds, will be on display. It comes from the renowned Muzo mines of Colombia, and was given to the sixth Duke of Devonshire by Pedro I, the Emperor of Brazil, when he came to Europe following his abdication in 1831.

The history of the Star of South Africa is even more exotic. A giant stone when uncut, it was found in 1869 in the region around the Orange and Vaal rivers in South Africa and prompted a rush to the region by prospectors hoping to find a similar lump of treasure. The 47.69 carat pear-shaped gem was cut and later bought by Louis Hond, the diamond cutter who first named the gem and re-shaped it into an 'oval, three-sided brilliant'. It was sold to the Earl of Dudley and his wife wore it as a hair ornament.

Finally, there are the rocks that fell to Earth. Among the meteorites on display is the Nakhla rock which fell out of the sky and hit Egypt in 1911. Scientists have recently discovered that its chemistry is identical to that of Mars and that it must be a piece of debris thrown into space when the planet was struck by an even larger meteorite.

At the time of its impact on Egypt, it was claimed that the meteorite had struck a dog which was killed, making it the only known fatality caused by a visitor from another planet.