Central Plains Diamond Micro Powder (Diamond Powder) Product Models: W0.25, W0.5, W1, W1.5, W2.5, W3.5, W5, W7, W10, W14, W20, W28, W40, W50, W60. Currently, W0-0.5 to W6-12 are generally used for polishing; W15-10 to W22-36 for grinding; and W12-22, the coarser grades, for fine polishing.