Synthetic diamonds: growth and etch phenomena

An account is given of interferometric and phase-contrast microscopic studies of de Beers synthetic diamonds. Some thousands of faces have been examined. Eleven growth spirals have been found on cube faces, step heights ranging from 200 to 1500 Å. Numerous cube faces reveal growth hillocks apparently not related to the spirals. Oriented dendritic-like overgrowths are reported and these are either dendritic diamond or else an epitaxial foreign growth with lattice matching reasonably with the diamond lattice. No spirals are found on octahedral faces but growth sheet layers are found of height 40 Å and less. Trigon growth on synthetic octahedral faces is very rarely found. Examples of extensive etching are reported on both cubic and octahedral faces and in some cases of diamond made in 1960 etching has proceeded so far that 10% of the initially grown crystal has been lost.