Research interest Thomas Stachel’s main research area is diamond geology. By studying the chemical and physical properties of diamonds (stable isotope composition, nitrogen contents and aggregation levels) and the geochemistry of their mineral inclusions, he seeks to define the conditions under which diamonds are formed and stored within the Earth’s mantle. Because diamonds form over a large depth interval extending from the deep lithosphere (>140 km depth) into the lower mantle (beneath the 660 km discontinuity), they provide a unique means of obtaining direct information on this otherwise inaccessible region of our planet