Raids on Paris jewellery stores increased to 716 in 2011 compared to 248 five years previously. The number of armed raids rose 25 per cent in 2011 to a total of 369. Three people were killed in three separate robberies last year.

The increase in theft is related to both the rise in the price of gold and the general economic situation.

One new anti-theft method now available to jewellers is a spray that covers attackers with an invisible fluid containing a tracer and a DNA code that can be detected under ultra-violet light for up to 120 days after the raid.