A JEWELLER, who left South Africa to escape violence and crime, was threatened with a knife and a screwdriver when he tackled thieves who stole a £12,500 diamond ring from his shop.

Tim Platten, owner of The Jewellery Workshop, High Street, Old Amersham, pinned down one of the thief's accomplices after he bolted from the shop.

But the South African had to let him go when the thief returned with the weapons.

He said: "We moved from South Africa to get away from this sort of incident, but now this has happened."

A young man, aged about 18 to 19, came into Mr Platten's shop last Friday and asked to see the ring.

Mr Platten, 33, was showing him the ring when another man was let into the shop. The first man grabbed the ring and made off with it in a waiting red Metro driven by another accomplice.

Mr Platten, who moved to England four years ago, said: "I managed to grab the thief's mate by his shirt and it began to rip. We ended up outside on the street and a fist fight ensued. At one point we ended up on a car bonnet."

The 6ft 2in South African was helped by a passer-by who held down the second man while the police were called.

But moments later the getaway car returned and the man who snatched the ring leapt out armed with the knife and the screwdriver.

Mr Platten added: "He threatened us with a knife and we let the bloke go. It wasn't worth it."

The 18-carat gold ring, with a 2.73-carat diamond in a traditional gipsy setting, was the largest in the window .

Mr Platten added: "At the time I thought it was a bit strange because not many young gentlemen can afford to buy a ring like that.

"I felt uneasy about the whole situation really."

One offender is described as white, about 5ft 8in, of slight build with short dark hair. The second was also white, about 5ft 6in, slightly built, with short dark hair and acne.

The red Metro was stolen from Tesco, Amersham, was later found dumped at Ashgrove picnic area, off the A413, Amersham.

Anyone with information should call Amersham CID on (01494) 465888