Dissolution of diamond crystals in a heterogeneous (metal-sulfide-silicate) medium at 4 GPa and 1400 degrees C

As a result of artificial dissolution of diamonds at 4 GPa and 1400 degrees C in a heterogeneous solvent (Fe-S melt with the addition of natural kimberlite in an amount of 5 wt%), it is established that, in the dissolution process the diamond crystals of octahedron form with flat faces and sharp edges are transformed into rounded octahedroids. The role of silicate additives is to local screen the surface of diamonds with the formation of etch hillocks, which gives crystals a visually complex external morphology. Thus morphologically complex natural diamonds with irregular shapes may form by dissolution by heterogeneous solvents in the mantle. Metal-sulfide-silicate melts consisting of immiscible components with different carbon solubility are the most likely candidates for such solvents.