Observation of etch channels in several natural diamonds

We report the characteristics of dissolution etch channels (open tubes), wi th various forms ranging from parallel lines to irregular ribbon or worm-li ke shapes, in seven natural gem-quality diamonds. These channel have openin gs at the surface with rhombic or modified rhombic shapes, and internally, they often terminate at solid inclusions. They appear to originate either f rom the outcrop of a bundle of dislocations, or along dislocation dipoles e longated along the (110) direction. As the dissolution process proceeds, th e penetration direction of an etch channel may change as a result of the in teraction with other growth defects. Many of the etch channels we observed exhibit highly irregular forms. Possible relationships between the etch cha nnels and lattice defects are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.