Africa was the major source of diamonds for most of the 20th century, but Australia and Sakha (of the Russian Federation) now produce about half the world’s supply. Also, most of the production today comes from primary sources (kimberlites and lamproite), whereas secondary (alluvial) sources dominated as recently as the early 1970s. Although the annual production of rough more than doubled in the 1980s, the production of rough yielding good-quality polished gems has not increased appreciably. The economic potential of a kimberlite or lamproite occurrence depends on the tonnage and grade of the ore, as well as on the quality of the diamonds it contains. The authors predict that the early 21st century will see the Russian Federation as an even more important source of diamonds and Canada as a major producer.