In this study, a 3M A3700 diamond disc was used to condition a Cabot Microelectronics Corporation D100 pad for 30 hours, and wear on its aggressive diamonds was analyzed. The top 20 aggressive diamonds for two perpendicular disc orientations were identified before wafer polishing, as well as after 15-hour and 30-hour polishing. Results showed that the original top 20 aggressive diamonds identified before polishing were subjected to wear after the first 15-hour polishing as the furrow surface area that they generated decreased dramatically by 47%. As these original aggressive diamonds were worn, seven new aggressive diamonds were "born" and joined the new top 20 list for both disc orientations. After the second 15-hour wafer polishing, the furrow surface area of these new top 20 aggressive diamonds did not change significantly. The furrow surface area created by all the active diamonds exhibited the same trend as the top 20 aggressive diamonds, confirming that most pad conditioning work was performed by these aggressive diamonds and that the disc lost its aggressiveness in the first 15 hours of polishing and then maintained its aggressiveness during the second 15 hours.