Hard disk substrates play a key role in the data storage process of magnetic storage hard disk drives (HDDs). However, a potential failure mode exists with the head clearance requirements caused by surface variation which is induced by substrate nano-asperities. Consequently, developing a polish process to eliminate surface asperities and residual surface defects in the glass substrate disks process is therefore a necessity to meet the challenges of future technology. Currently, the leading candidate utilizes nano cluster diamond (NCD) abrasive which is a synthetic diamond created in a controlled explosion process. A great effort is now underway to modify these NCD clusters to reduce light scratches and asperities in the perpendicular magnetic recording media polish process. Three distinct diamond types of NCD-90, NCD-80 and NCD-70 were utilized in this study. The major difference among these three distinct cluster diamond types is the diamond percentage amounts. Because of the differing diamond percentage content, one achieves a different structure which changes the polish properties. HRTEM, XPS, Raman, BET, AFM, Optical Surface Analyzer and disk defect testers were used for the diamond particles, polished substrate and disk analysis. The detail shall be discussed in this study.