A substantial reward is being offered after four diamond rings, together worth £3,000, were stolen from an Ashburton jewellers.

The 18ct gold rings were snatched from the Silver Lion window display at noon on Wednesday, June 17, while shop assistant Sue Woodfield was serving a customer.

Owner Jane Bark said they were unusual rings – hand-made by a jeweller who lives in Ashburton – and represented her aim to offer a more bespoke service.

One, scattered with coloured diamonds, cost £695; the second at £480 was white gold with white diamonds; the third at £850 was a 'rub-over' setting with six small and one large diamond. The fourth at £980 was a conventional solitaire.

Mrs Bark said: 'I was in the process of getting an extra security door fitted. A man came to fit it half an hour before but had to take it away again because he said it didn't fit.

'We figure the theft had been set up. A girl in her late 20s or early 30s came in and stood in the way of the camera, in front of the access [to the window display]. My associate was serving somebody and asked if she needed help. She said, no, she was waiting. Then a man put his head round the door and shot out again.

'Sue didn't think anything about it until she went to replace one of the displays and realised the rings had gone. The girl had by then walked off very quietly.'

The rings were uninsured and Mrs Bark is offering a substantial reward for their return.

'I'm hoping somebody out there will have a conscience. It's hit my business very hard. For the first couple of days I could hardly talk about it.'

The shop's security cameras have been upgraded and the window display security door has now been fitted.

Mrs Bark, who was recently made vice-chairman of the town's chamber of trade, said: 'I was aware we were vulnerable. I was busy in Plymouth doing a show called the Beautiful Journey. I took my eye off the ball.'

Police are examining cctv footage.

A spokesman said: 'There is nothing to suggest that the young lady went in purposely to block the camera but she is somebody we would want to speak to as a potential witness.'

She is aged about 25/35, described is white, 5ft 5ins, of average build, with long fair hair with a blunt fringe.

The suspect is white, 6ft with short dark hair, a skinny build, in his 20s, and wearing a dark coat, similar to a duffle jacket.

Anyone with information is asked to contact PC Andy Dudley on 08452 777444 quoting crime no JA/09/245.