Concentration is the ratio of the weight of the Diamond or of the CBN in carat (1 carat = 0.2 g) to a cubic centimeter of grinding rim volume. According to FEPA Standard / standards concentration "100 for Diamond" resp. "240V for CBN" corresponds to an abrasive content of 4.4 carat per cubic centimeter of grinding rim volume. All other concentrations are proportional. Concentration has a considerable impact on the cutting performance and the life of a grinding wheel, to some extent also on the price.
The bar diagram shows the different concentrations.