A rare Chinese cup, dating back to the Ming Dynasty and found covered in dust at an English university, was sold at an auction in Hong Kong Tuesday for more than $4.6 million. [File photo]

A rare Chinese cup, dating back to the Ming Dynasty and found covered in dust at an English university, sold at an auction in Hong Kong Tuesday for more than $4.6 million, the university said.

The Staffordshire University in central England said the Stem Cup dates back to 1425-1435 and bears the six-character mark of Emperor Xuande.

The cup was part of a collection of oriental ceramics donated to the university by London Chemist Ernest Thornhill in the 1940s to prevent damage from the German Blitz on Britain's capital in World War II.

Ceramics expert, professor Flavia Swann said the antiques had been discovered after a chance conversation with the head of the Ceramic Technology Department.

She said it was only after they said: "I've got some dusty old pots cluttering up my corridor, would you like to have a look?" that the treasure haul was discovered.

The pots, including the cup, were put into storage at the university. The cup only emerged again last year when it was revalued.

The remaining collection is stored at a secret location.

Auctioneers Lyon & Turnbull had valued the cup at around $2.9 million.