Gem businessman is convicted thief

David Unwin bought Wrekin in 2007 and transformed the Lamledge Lane construction firm's balance sheet into showing a profit when his Tamar group sold Wrekin a 4.5lb uncut ruby, known as the Gem of Tanzania, in exchange for £11 million of shares.

But when the company collapsed into administration in March with the loss of 500 jobs, it was found to have debts of up to £40 million, £20 million of it owed to the Wrekin pension scheme.

The ruby is now thought to be worth just a few hundred pounds as a curiosity and is up for sale on a gem enthusiasts website.

Meanwhile Mr Unwin has been revealed to have a conviction for theft dating back to 2002. In April of that year he was convicted of 10 counts of theft, involving the sale of £1.2 million of construction plant owned by a finance company.

At Stoke Crown Court he was sentenced to 12 months in jail, suspended for two years, and was ordered to pay £10,000 towards the cost of the prosecution.

At the time he was building up his Derbyshire-based construction group Tamar, which has become one of several businesses connected to Wrekin to have now gone out of business. Mr Unwin's Tamar Group bought Wrekin for £150,000 when the company was millions of pounds in the red and facing administration.

The share-swap deal for the Gem of Tanzania transformed its balance sheet.

But the valuation of the ruby at £11 million was a huge increase on the £300,000 it was worth in Tamar's accounts just 12 months earlier.

Mr Unwin has said he was the victim of fraud over the valuation of the gemstone.

West Mercia Police's economic crime unit has said it is currently in contact with the administrators of Wrekin Construction, accountants Ernst & Young. But as yet, no formal inquiry has been launched.

A force spokeswoman said today: "No formal inquiry has been started but we are looking in the circumstances."