Diamond worth £2m found during Northumberland home clearout

The 34-carat diamond had been kept in a box alongside items of costume jewellery by its unwitting owner

A woman who bought what she thought was a costume jewellery stone is set for a £2m windfall after tests revealed it is a 34-carat diamond.

Its owner, who is in her 70s, had been clearing her home in Northumberland and took it to be valued, along with other items she had bought at car boot sales over many years.

Auctioneer Mark Lane said its true worth had come as a "huge shock".

The gem, which is bigger than a pound coin, is being auctioned next month.

Mr Lane, of Featonby's Auctioneers in North Shields, North Tyneside, said: "The lady came in with a bag of jewellery as she just thought she would bring it in as she was passing because she had another appointment in the town.

"It had been in a box along with her wedding band and a number of low-value costume jewellery items.

"We saw quite a large stone, bigger than a pound coin, and I thought it was a CZ [cubic zirconia, a synthetic diamond lookalike]. It sat on my desk for two or three days until I used a diamond tester machine.

"We then sent it off to our partners in London before it was certified by experts in Antwerp, Belgium, who confirmed it is 34 carat."

The carat measurement relates to the weight of the stone, whereby heavier stones have a higher carat and higher value.

The diamond has been assessed and certified by experts in Europe

Mr Lane said the stone's owner, who wanted to remain anonymous, could not recall where or when she acquired it.

"She's always visited car boot sales and bought trinkets, but never once did she think it was a real diamond.

"She told us she'd been having a clearout and that it nearly went in the bin before her neighbour suggested bringing her items to us to get valued."

'Off the scale'

Mr Lane, who has run the business for five years after buying it from its previous owners, added it was by far the largest-value item he had dealt with.

"The colour, the clarity, the size... to find a 34-carat diamond is off the scale."

The diamond is being kept under lock and key at London's Hatton Garden jewellery quarter until it comes up for auction on 30 November.

Auctioneer Mark Lane said he was shocked by the discovery