A THIEF in Winchester has made off with a £30,000 diamond ring, thought to be the biggest single theft in the city's history.

The ring was stolen from Jeremy France Jewellers on Tuesday afternoon after the thief entered the shop posing as a customer.

Now police in Winchester are seeking witnesses to the incident, who may have seen the man fleeing the shop before bounding into a get-a-way car and careering out of the city.

The ring in question, a white diamond solitaire, is not only the biggest and most expensive ring the jewellers have ever stocked, it is also thought to be unique.

Set in solid platinum, a rectangular two-carat phoenix cut diamond with 89 facets sits in the centre of the piece, flanked by two further pear-shaped white diamonds.

The man had approached the 18-year-old shop assistant in the jewellers on Upper High Street and asked her to let him examine the ring, along with another similar piece valued at just under £20,000.

Feeling out of her depth, the assistant asked the man to wait while she got the shop's owner, Jeremy France, but as he approached, the thief leaned over the counter, grabbed the ring and fled through the front door.

Mr France chased after the man, described as 25-years-old, about 5ft 10in in height, of proportionate build and with his upper right front tooth missing, up the High Street and into Tower Street.

However, as they turned the corner and as Mr France had just got hold of the man, Mr France slipped and the man made it to a M-reg white Ford Mondeo car, which then sped off spinning its wheels.

Police in Winchester are now keen to hear from anyone who saw either the incident itself, the chase, or the White Mondeo fleeing the city along Sussex Street, Romsey Road, Upper High Street or any of the roads out of the city at 3.20pm on Tuesday.

Mr France said: "It was a normal day and the shop had about seven or eight customers in it.

"The man came in and asked to see these specific rings, however, when my member of staff realised the rings were out of her depth, she asked me to come over.

"But, as I did so, the man grabbed the more expensive ring - in fact it's the most expensive ring we've ever had in - and ran off.

"I chased after him all the way along Tower Street and almost caught him, but I slipped going around a corner and he got to the car and got away.

"Thankfully no one was hurt in the incident, and we just hope the police catch up with him as soon as possible."

Anyone with any information or who witnessed the incident is asked to contact Winchester CID on 0845 045 4545.