In the 1940s and 1950s, several Soviet expeditions went out in search of volcanic rock kimberlite. The existence of kimberlite generally signifies that there are diamonds below the surface. While most expeditions failed, one expedition succeeded immensely.

It was on this day, June 13th, in 1955 that the first Russian diamond mine, Mir Mine, was discovered. Soon thereafter, the mine produced $600 million worth of diamonds a year.

Mir Mine operated for 44 years. It is no longer active, but it remains the second largest excavated hole in the world. Its 525 meter deep and 1,200 meter deep hole is only exceeded by the Bingham Canyon Mine.