Introduction: Diamond of metamorphic origin in supracrustal rocks was first discovered from the Kokchetav Massif in the Caledonides of northern Kazakhstan. Microdiamond-bearing rocks include biotite gneiss, garnet mica schist, pyroxene marble, and garnet pyroxenite; no diamond has been reported in the associated metabasaltic eclogitic rocks (e.g., Sobolev & Shatsky, 1990). We have selected 3 eclogites, 5 garnet-bearing gneisses and 2 pyroxene marbles collected from Kumdikol of the northern Kokchetav Massif during the 1994 field season for detailed study for two purposes: (1) to determine whether or not the microdiamonds were formed within the diamond stability field; and (2) to delineate the retrogressive P-T path.