A system for calculating control pulse duration for optimal stepper motor performance. The FPC 116 is connected at one end portion thereof to an optical pickup 115 and is extended in one of feeding directions thereof, curved and turned back intermediately and then extended in the other one of the feeding directions. The acoustic wave is received at the microphone to estimate an acoustic pressure response. A loudspeaker using the diaphragm is also disclosed. An imaging device is arranged to obtain images of the gemstone at the observation position at a variety of relative rotational positions between the illumination structure and support structure: the imaging device has an imaging axis passing through the observation position. The process involves separating succinic acid from the other organic acids and salts in a raw filtered broth using a non-functionalized chromatographic resin.