Evaluation of gravity separation of minerals usually is accomplished with two indices. The first is liberation degree and the second is separation accuracy or Escort Probable (Ep). This research is a case study on ALBORZ_E_SHARGI coal washing plant wastes for the evaluation of two essential indices. It was found that the indices representing a numerical value can^'t give sufficient information required for decision. Thus efforts took place to improve previous indices and to represent a method for accurate characterization of feed. It was obtained a suitable product for steel industry in two stages. Gravity concentration step by cut point of 1.75 t/m³ is necessary to produce primary concentrate followed by grinding it to -2^mm and rewashing to obtain final concentrate.  In the first step ash content reduced from 66% to 31.3% and the reduction of ash content to 14% in final washing was possible.