The Diamante river is an Argentine river, in the province of Mendoza. It is born from glaciers in the Maipo volcano, on the Argentine-Chilean Andean border, and flows east until it empties into the Desaguadero river. It has a hydrographic basin of 2,750 km² in the central region of Mendoza.

El Diamante feeds on the thaw that enters Diamond Lake. It has a flow of 33 m³ / s, with maximums in spring and summer; between October and March it accounts for 70% of the annual volume of water.

The upper course of the river goes south and ends going north, and enters the deep and narrow 'Agua del Toro Canyon', where it is used to produce hydroelectricity by the Agua del Toro Reservoir, at 69 ° W, downstream in the Los Reyunos Reservoir. Together they generate 500 MW.

Upon reaching the plain, the Diamond loses part of its flow through infiltration and evaporation. It makes a great arch, passes to the south of the city of San Rafael, in the geographic center of the province of Mendoza, where it is used for irrigation (along with the Atuel river).

The river opens in multiple arms shortly until it reaches the Desaguadero (here called Salado), on the border with the province of San Luis.