The form of grinding grains is an important parameter which as show researches, has a great impact on efficiency of use of grinding tools. Generally the methods used for an assessment of a form of grinding grains can be divided into two groups – qualitative and quantitative. The principle of an assessment of a form of grain on qualitative methods is based on grain reference on some signs in the relevant group of forms. All existing ways of a quantitative assessment of a form of grain are based on research of a horizontal projection of grain. However application of horizontal projection results in inaccuracy in the analysis of a form of abrasive grain. This work is devoted to accuracy increase at an assessment of a form of grinding grains.