Hong Kong criminal 'swallowed Siberian diamond' to steal it from St Petersburg exhibition

The heist was at the Junwex jewellery industry exhibition in St Petersburg and the 3.1 carat stone vanished after being examined by a pair from Hong Kong. 

They asked to examine to diamond, using a magnifying device, appearing to be professional jewellers seeking to buy it. After looking at it closely, one of the well dressed pair said: 'Let's get it.'

But then a woman said: 'We need to think a bit longer.' In fact, the pair had aroused the suspicion of security staff who were watching the Diamonds of Yakutia stall. 

Staff checking the stone found it had been substituted with a perfect fake copy, suggesting the operation was long planned.

Lu Limei, a 30 year old woman, was arrested at the exhibition and her male companion named as Lu Bo was held at the city's Pulkovo airport. Searches showed they did not have the stone. 

They were taken to hospital and ordered to take evacuant medicine amid suspicions that they swallowed the diamond. Yet police failed to find the diamond. 

However, investigators now believe Lu Bo had put the stone in his mouth but not swallowed it, before passing it to a third member of the gang, a woman. She took the gem by the train to Moscow before flying to Hong Kong, and is also suspected to have swallowed it. 

She was arrested in Hong Kong but with no evidence of the diamond. 

Valery Budny, the president of Restek Juniwex: 'It is not that easy. For example if you put a diamond into a glass of water, you won't see it at all. It is much harder to find it in the human body. 

'We know that the works of Russian jewellers are highly popular but we would prefer this interest to remain within the legal field and to avoid the interest from the criminal world.'

The group are known to have travelled previously to Russia, and to have visited earlier diamond exhibitions. Yakutia - officially called the Sakha Republic - is famous as the source of Russian diamonds.