Both men were convicted of conspiracy to rob - a third escaped

Serbian-born Nebojsa Denic, 34, was convicted at the Old Bailey on Tuesday of conspiracy to rob Graff's in Mayfair, in May 2002.

Milan Jovetic, who admitted helping a third man escape with the gems, was sentenced to five-and-a-half years, also for conspiracy to rob.

Only �3m worth of the stolen jewellery has been recovered.

A �500,000 blue diamond ring was found in a tub of face cream belonging to Jovetic's girlfriend at his house in Bayswater, west London.

The staff have been, in different ways, markedly and perhaps permanently affected by what you did Judge Gerald Gordon

While Marco escaped, Denic was caught by two security guards who managed to hold him despite the fact he had a gun.

Jovetic, the son of a wealthy businessman in Montenegro, then helped the escaped man flee to France.

The court heard French police have arrested a man in connection with the robbery.

Loaded gun

Sentencing, Judge Gerald Gordon said the men had played for "high stakes".

He told Denic: "To achieve your ends you took with you a fully functional and loaded Magnum .357.

"Not surprisingly, your use of it succeeded in subduing staff who were terrified and have been, in different ways, markedly and perhaps permanently affected by what you did."

Denic was sentenced to 15 years in prison for conspiracy to rob, six years for possessing a gun and seven years for using it to resist arrest - all to run concurrently.

'Remarkable courage'

Jovetic received a five-and-a-half year jail term for conspiracy to rob and three years for handling the ring, also to run concurrently.

The judge also recommended that Denic, who had arrived in the UK on a tourist visa, should be deported after completing his sentence.

Judge Gordon awarded �700 each from public funds to security guards Simon Stearman and Clinton Delo for their "remarkable courage" in aiding the arrest of Denic.

He also said �7,000 recovered from Jovetic's house should be shared between the two guards.