A Houston man pleaded guilty Tuesday for his role in a multimillion-dollar diamond fraud scheme involving two men from the Dallas area.

Christopher Arnold Jiongo, 55, faces up to 20 years in prison and a $250,000 fine for one count of wire fraud. His sentencing is set for Sept. 11.

Christopher Jiongo (LinkedIn)

Co-defendants Craig Allen Otteson, 64, of McKinney and Jay Bruce Heimburger, 58, of Dallas are awaiting trial.

According to court documents, Otteson acted as the chief executive of Stonebridge Advisors, which served as the managing partner of Worldwide Diamond Ventures in Far North Dallas. Heimburger was the director of JBH Securities and provided investment advice to Worldwide Diamond.

From 2011 to 2012, the men fraudulently collected millions of dollars, court documents say. The scheme started in summer 2011 when Jiongo drafted $50,000 diamond notes to generate investment funds.

The men defrauded nearly 80 investors by concealing information from them, including how their money would be used, authorities say.

While promising the money would go toward diamond investments, the men allegedly used the money to make loans up to $2.4 million to third parties and transferred funds to bank accounts controlled by Jiango.

According to the Texas Bar, Jiango has a law office in downtown Houston.

Otteson and Heimburger also face charges of mail fraud. Their trials are scheduled for July.