The world's greatest rock show!

The world's biggest set of priceless diamonds will arrive at the Natural History Museum next month amid a massive security operation. The collection features a range of the world's biggest diamonds and royal gems lent to the museum especially for the event.

"It's the first time that this many priceless stones have been together, and the breadth of the diamonds we have is amazing," said Professor Andy Fleet, the museum's keeper of mineralogy.

"People have an amazing fascination with diamonds and have done throughout history. We will be focusing largely on coloured diamonds, which are rare."

Only one coloured or "fancy" diamond is mined for every 10,000 white diamonds and they are the most valuable gemstones in the world. Visitors are warned to expect several security checks. "We really couldn't put a price on these diamonds - they are akin to pieces of great art," said Professor Fleet.

"As you walk into the exhibition, there will be about 12 of the the key diamonds from around the world on display, but there are hundreds more.

"We will chart the fascination with diamonds, and also explain where they come from. Obviously, with that many incredibly valuable pieces, security was a big issue for us."

The display will feature the pumpkin ring worn by Halle Berry when she received her best actress award at the 2002 Oscars and rings worn by Sharon Osbourne.

The exhibition is due to open in July and will run until February.