Former executives of Tanzanite One have launched a shareholder insurgency against the Aim-listed gemstone miner, offering rival Gemfields another chance at acquiring Tanzanite One after a messy takeover battle failed last month.

An entity holding the shares of Mike Nunn, Tanzanite One’s founder and its largest shareholder, on Thursday called a special general meeting to propose dismissing most of the company’s board because of the way it handled a hostile bid by Gemfields, an emerald miner trying to become the leader of the coloured gemstone market.