Type Ib synthetic diamonds from De Beers with a low dislocation density have been deformed under confining pressure under pressure of 5 GPa in a multianvil apparatus between 900 and 1200 °C and in a D-DIA experimental set up at 1100 °C and strain rate of 7 × 10−5 s−1. TEM observations of diamond deformed at 1100 °C, the lowest deformation temperature where plasticity was unambiguously evidenced are reported in this work. Two types of dislocations have been found to coexist: dissociated and perfect. No large stacking faults resulting from the dissociation splitting blow up under large stress have been observed. Numerous dipoles are found in the microstructure which can be built with perfect or dissociated dislocations. These results are discussed in relation with dislocation core configuration calculations.