At the Synchrotron Radiation Source in Daresbury, England, we scattered x-rays from the synthetic diamond samples.  We looked at the x-rays scattered at the Bragg angle, where there is a high intensity of reflected x-rays because reflections from the crystal’s many planes interfere constructively.

First, we exposed photographic plates at the diamonds’ Bragg angles.  Patterns of dark and light in these photographs indicate stresses in the crystal, whereas a uniform exposure indicates a crystal with few stresses.

Next, we moved the crystals slowly through their Bragg angles and measured the intensity of the scattered x-rays as a function of angle.  A narrow Bragg peak indicates a crystal with a regular lattice structure, but a wide and irregular peak indicates imperfections in the crystal.