2kg ruby named as asset by Wrekin construction is worth "about £100"

The Gem of Tanzania, a 2kg ruby with a valuation of £11m that once underpinned the finances of failed building firm Wrekin Construction now looks to be worth closer to £100, according to reports.

The Financial Times said that the stone was rejected for sale by the big London auction houses because it was not worth enough. It claims the stone is incapable of being cut into jewellery. Instead, it will be sold in the pages of Rock 'n' Gem magazine, which is read by mineral collectors and New Age crystal healing enthusiasts.

Businessman David Unwin used the gem to buy out Wrekin in 2007 after presenting documents that indicated it was worth £11m. It had previously been valued at £300,000.

Wrekin went into administration earlier this year and the gemmologist whose name appears on the bottom of valuation documents told Building they papers were forged.

The police said that they were considering whether to mount a fraud case.

Marcus McCallum, a Hatton Garden gem dealer, told the FT: “The Gem of Tanzania may not be worth the cost of the advert.”