The Cerchar test is increasingly being used as a method to assess the abrasivity of rock in drilling and machine mining applications. A study was undertaken to determine the effect of changes in the metallurgy of the steel styli that is used in the test procedure on the Cerchar Abrasiveness Index (CAI) value. The study involved testing seven different metal types heat treated to the same hardness level and one steel type at nine different hardness levels. The study found there was little change in the CAI value with different steel types however hardness of the steel styli was found to affect the CAI value. CAI varied inversely with hardness of the steel styli.