Crystal sizes can be calculated from peak intensities of spotty diffraction rings produced by a polycrystalline sample. Such patterns are collected using a small X-ray beam and an area detector. Peak intensities can be automatically measured using specially designed software. Crystal sizes can be determined from peak intensities after calibration using samples of the same material whose sizes are already known. This technique is independent of the aggregation state of the material. Also, crystal sizes of different mineral phases present in a sample can be analyzed independently. The present paper analyzes the potential of this methodology as applied to crystal size characterization of crystalline powder materials. Graded SiC and alpha-Al2O3 abrasive powders were selected as test material for this study. A high correlation was found between parameters determined by X-ray diffraction and crystal size determined by means of optical microscopy and laser diffraction. The crystal sizes determined ranges from 3 to 80 mu m, a much larger range than that obtained by conventional X-ray line-broadening analyses. Additionally, upper and lower size ranges of applicability of this technique can be extended further by using different collimator diameters. The estimated error in crystal size measurements was within 5%.