Plastic deformation in natural diamonds: Rose channels associated to mechanical twinning

• Voids of ≥ 100 μm and sometimes ≥ 1 mm long are observed in some natural diamonds.
• These concave voids are demonstrated to be Rose channels created under HPHT.
• Their {110} directions agree with two twinned lamellae intersections.
• Mechanical twinning in natural diamonds is not only restricted to pink diamonds.

Hollow channels in diamond are well acknowledged to be the result of dissolution processes. In this article we demonstrate that some hollow channels in natural diamonds are the consequence of intense plastic deformation by mechanical twinning. Two mixed-habit diamonds presenting numerous geometrical hollow tubes were studied. X-ray Laue analyses showed the presence of microtwins. At the intersection of microtwins, displacements and cracks are generated, creating the hollow channels observed. The presence of the cracks seems to have released the internal stress, as there was less to no signs of deformation at and around them. Further dissolutions are sometimes but not always seen within the cavities. Mechanical twinning, so far mostly identified in pink to purple diamonds, might be more widespread than originally thought in natural diamonds.

Macroscopic voids (≥ 100 μm in diameter, and sometimes ≥ 1 mm long) are observed in some mixed-habit growth natural diamonds. The voids are created at the intersection of two twins and are interpreted as Rose channels. This figure shows cross sections of the Rose channels by scanning electron microscope imaging and their interpretation.Figure optionsDownload as PowerPoint slide