The stolen tiara - the most valuable piece from the robbery that netted jewellery worth about £250,000 - was made in the late 19th century and has been in the Norwegian royal family since 1896. Queen Sonja is a regular customer of Garrard's and the theftis an embarrassment for the company.
The tiara was part of the Queen's personal collection, not the Norwegian crown jewels.
During the raid three people, including a robber dressed as a policeman, ambushed and tied up two security guards before fleeing with the jewellery. About 70 armed police officers later laid siege to the shop for five hours before entering the empty premises.
Commander Tony Rowe, who is leading the hunt for the robbers, yesterday defended his officers against criticism that they had taken too long to discover that the robbers had left the building.
Mr Rowe said he was not embarrassed and that his officers had responded to the alarm call within "a couple of minutes" and had followed police procedures properly to avoid any risk to the public.
He said: "I would have been gravely embarrassed if they had escaped through lack of awareness or if a member of the public or one of my officers had got shot because we were careless in what we did."
The blue Volvo car believed to have been used for the getaway had been found in Farringdon Road in the City. The police are examining the possibility that the raiders had inside information. A "substantial reward" has been offered for the recovery of thestolen items.Reuse content