Dallas (WBAP/KLIF) – Two north Texas residents are going to prison for running a diamond investment scam. Craig Otteson and Jay Heimburger each pleaded guilty in July to defrauding investors in Worldwide Diamond Ventures out of some $6.5 million. They were sentenced Thursday. Otteson got ten years in federal prison. Heimburger was sentenced to eight years. In addition each man was ordered to pay more than $4.5 million in restitution. A third defendant in their scheme will be sentenced November 21.