Juan Guardarrama, 49, had been charged with more than a dozen felonies, including racketeering, money-laundering, dealing in stolen property and soliciting first-degree murder, El Nuevo Herald reported Tuesday.
Guardarrama pleaded guilty to most of the counts involving a jewelry ring. Prosecutors dismissed charges related to marijuana and soliciting murder.
He will have to surrender about $2 million in jewelry and money confiscated from his apartment in Denver, the report said.
The judge reduced his potential prison sentence to 10 years after Guardarrama agreed to work with authorities on other cases involving the stealing and fencing of diamonds.
He had faced more than 30 years in prison.
Guardarrama had been under investigation for more than four years by a multiagency task force when he was arrested in June at a Miami Beach hotel.