Kimberlites are the most deeply derived of all volcanic rocks, as well as the host rock for most of the world’s diamond mines. Kimberlites, therefore, provide unique snap-shots of magma genesis and mantle evolution in the deep Earth well into the diamond stability field (>150 km and, potentially, >700 km). Despite over 100 years of study, the origin of this complex rock-type remains the subject of intense debate. This thematic issue will summarize current knowledge and controversies on kimberlite formation, including key aspects of the petrology, geochemistry and volcanology of these unique rocks. It will show how kimberlites can be successfully dated, and explore links between the temporal and spatial distribution of kimberlites and known geological events. Diamond exploration and resource evaluation methods will be reviewed to demonstrate the inextricable link between an accurate understanding of the characteristics of kimberlites, their entrained mantle cargo, and diamonds.