An “unassuming lady” from St Albans was left speechless after a piece of costume jewellery left ignored in a bottom drawer for decades was sold for thousands of pounds at auction.

It was later discovered that her tiara was a rare item, encrusted with diamonds including a half carat stone, possibly dating back to the Edwardian era.

Auctioneer Jonathan Humbert, of J P Humbert Auctioneers, said the firm had been holding a free valuation day at the Town Hall when, “a small box was brought in by an unassuming elderly lady”.

“The auction house gave the item an estimate of £1,500-£2,000, and it was successfully sold for £3,400.”

Jonathan said the debutante tiara given to the lady as a birthday present was, “cleverly made so the diamonds could be detached to form separate brooches”.

He said there was a lot of international interest in the tiara but it was sold to a jewellery business in London.

Jonathan added: “When I rang her to tell her what it had sold for, there was a stunned silence. She thought I was joking and asked, ‘what did it really sell for?’ It took some time to convince her what it had sold for, and she was absolutely delighted.”

He urged other residents to look out for high value items left languishing in their homes, “as the market has never been more hungry for gold, silver, jewellery and watches”.

The auctioneers are hosting another valuation day on Wednesday, November 6, at the Town Hall, 10am-2pm.