The armed robber at the Carlton Hotel in Cannes targeted a temporary jewellery exhibition it was hosting from a diamond house owned by Israeli billionaire Lev Leviev.
It remains unclear how many pieces were stolen.
The valuable jewels were due to be on public display until the end of August.
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It will be a dull and damp day today, with heavier and more persistent rain to the northwest and across Wales.
The privatisation of Royal Mail was handled with "considerable professionalism" , says a report from Labour's former City Minister.
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