LONDON, July 6, 2007 (AFP) - Two armed robbers tricked their way into one of the British capital's most exclusive jewellery stores and stole millions of pounds (euros, dollars) worth of designer gems, British police said Friday, July 6th.

A rare aquamarine and diamond blangle, circa 1935 by Cartier Photo : Fabrice Coffrini/AFP

The smartly-dressed pair -- one dressed in a Panama hat and blazer -- were admitted to Graff Diamonds in upmarket Sloane Street, west London, at about 5:10 pm (16:10 GMT) Thursday, July 5th expressing interest in jewellery on sale.

But once inside they pulled handguns on staff, including a security guard, helped themselves to designer gem-encrusted pieces and then let themselves out, the Metropolitan Police said.

Exact details of how much was taken were not released but Detective Sergeant Sarah Staff said: "We are talking something you would be able to carry but it is a substantial amount, a very, very high value."

The haul included diamonds, rings, necklaces, pendants and earrings studded with precious stones.

In their first edition Saturday, July 7th, The Sun and the Daily Express tabloids valued the haul at 10 million pounds (14.7 million euros, 20 million dollars)

Graff is based in New Bond Street, central London, and has a number of branches worldwide, including in New York, Monte Carlo, Dubai, Kuwait and Moscow.

It specialises in producing polished diamonds from the rough stones and has a 300-strong team at its own diamond cutting facility in Johannesburg, South Africa.

Owner Laurence Graff has been dubbed the "king of diamonds".

He says on his company's website: "Diamonds excite me, diamonds are my life -- I see inside the stone, look at the colour and cut and assess its natural beauty and value -- I was born to be amongst diamonds."

In 2003, robbers got away with a six-million-pound haul from Graff's flagship New Bond Street store. A gang also stole seven million pounds worth of gems from one of its London workshops in 1993.