Diamonds and other precious stones forming part of a Czech National Museum collection thought to be worth millions of pounds have been exposed as fakes during a routine audit.

The inspection of supposed 5-carat diamonds and a 19-carat sapphires has left curators scratching their heads as to how the real things went missing over the last 50 years.

Around half the museum’s collection, acquired by the museum during communist times, has already been found to be fake.

The museum is now trying to discover if it was victim of con artists during the acquisitions, or even if the apparent heist was an inside job sometime in the last five decades.

The collection was located at different sites over the years, but since 2011 has sat in a secure depository on the outskirts of Prague, Mr Macek told The Telegraph.