The characteristics of dissolution etch channels (open tubes), having forms ranging from parallel lines to irregular ribbon-like or worm-like shapes, were studied in 7 natural gem-quality diamonds. The channels had openings at the surface, of rhombic or modified rhombic shape. They often terminated at internal solid inclusions. They appeared to originate either from out-crops of bundles of dislocations, or along dislocation dipoles which were elongated in the [110] direction. As dissolution proceeded, the penetration direction of the etch channel could change as a result of interaction with other growth defects. Many of the etch channels exhibited highly irregular forms. The relationship between etch channels and lattice defects was considered.

Observation of Etch Channels in Several Natural Diamonds. T.Lu, J.E.Shigley, J.I.Koivula, I.M.Reinitz: Diamond and Related Materials, 2001, 10[1], 68-75