The main object : of all industrial crystallization process is to produce crystals with desired properties such as crystal size distribution (CSD), shape and purity. The CSD is determined by the rates of nucleation, attrition and breakage, agglomeration, and growth. The intention of this paper is to focus on nucleation, metastability and crystal growth with the objective of defining ranges of optimal supersaturation with respect to product quality. Agglomeration call play an important role but will be omitted in this article.