A Toronto founder of a large diamond investment fraud that swindled more than $21 million from about 200 victims — many of them seniors duped over the phone — has been sentenced to 56 months in a U.S. prison.

James Gagliardini launched a company in 2013 that defrauded people for years through conmen convincing unsophisticated investors to send them ever-increasing amounts of money for coloured diamonds, lying that they were worth far more than they were and that a huge profit was just over the horizon — but they always needed to spend more to get there.