A varisized diffusion cell device (10) comprising a plurality of diffusion cells (18) arranged in rows (20A) to (20F) having progressively greater depths for growing high quality, diffraction grade crystals, is described. In use, the diffusion cells receive a quantity of crystallizing agent (32) that dissolves and diffuses through a head of solvent solution (34) to equilibrate with a drop (38) containing a subject macro-molecular material for growing crystals. The various depths of the diffusion cells provide various diffusion rates and therefore various equilibration rates. Through empirical methods, an optimum diffusion rate for a given crystal growth system can easily be determined.