Diamantino is a municipality in Mato Grosso state in Brazil. It has a population of 22,178 and is near Diamantino River. It is 1,837 feet ab…Diamantino is a municipality in Mato Grosso state in Brazil. It has a population of 22,178 and is near Diamantino River. It is 1,837 feet above sea-level, and sits at the foot of the Mato Grosso plateau. Its history dates from 1730 as a gold mining settlement. In 1746, diamonds were discovered, which made the town's population swell and prosper. The amount of diamonds was greatly overestimated, and the town population steadily declined.