THE mystery of a ruby, said to be worth £11m, deepened last night.

The gem is reputed to be owned by Wrekin Construction – the company behind the ill-fated £4m revamp of St George’s Square.

The company limped into administration last week and as yet, work has not restarted on the Square project, now being managed by Kirklees Council.

But more attention is now being focussed on the mystery “Gem of Tanzania”, which according to the Wrekin books was worth £11m.

It emerged the gem was valued at only £300,000 just a year previously. And a claim in Wrekin’s 2007 accounts that the gem was valued by the Instituto Gemmologico Italiano in Valenza was dismissed.

Loridana Prosperi, a gemologist for the group, has said that would have been impossible since the office was closed that day.

Reports suggested the “Gem of Tanzania” had revived the balance sheet of Wrekin Construction.

In 2006, the precious stone belonged to Tamar Group, a vehicle of businessman David Unwin. Their 2006 books report a gem worth £300,000. Mr Unwin took over Wrekin in 2007, when it issued £11m in preference shares in return for the stone.

Wrekin’s total assets, according to its 2007 accounts and including the £11m ruby, were about £28m.

But auctioneers Christie’s said the highest recorded price for a ruby was £2.6m in 2006.

Days after the Wrekin Group went into administration with the loss of around 400 jobs, no-one is certain where the gem is, or indeed able to recall having ever set eyes on it.

Ernst & Young, Wrekin’s administrator, says it is looking into “a number of issues which have already been identified” but not specifically whether staff are checking drawers and waste paper bins for the elusive stone.

A spokesman at Tanzania’s high commission in London said he had never even heard of the stone, also reportedly known as the Star of Zanzibar. “We do have a lot of rubies in Tanzania, but I’ve never heard of that one,” he said.