In which region are Russia's significant diamond deposits primarily found?

Russia's significant diamond deposits are primarily found in Siberia, which represents a major region for diamond mining in the country. The Siberian region, particularly the Yakutia area, is home to some of the largest diamond mines in the world, including the Mir and Udachny mines. The harsh conditions and vast landscapes of Siberia have not deterred extensive mining operations, as this region holds a substantial portion of Russia's diamond resources.

In contrast, other regions mentioned do not serve as significant sources for diamonds. For instance, the Ural Mountains and the Volga River Basin are known for different kinds of mineral resources. While the Caucasus Mountains may contain some mineral deposits, they are not recognized for substantial diamond resources, especially when compared to the prolific deposits found in Siberia. This context reinforces why Siberia is considered the primary region for Russia's diamond deposits.