This might surprise you, but while I want to maintain true to Diamondhead's deep voice, I also wanna give him more personality. Look at Roger Craig Smith's attempt on Diamondhead in the new Ben 10 Reboot.

Diamondhead can transform his body to create diamond-like weapons such as blades and bludgeons. He can also fire lethal crystal shards from his hands and resist attacks with his sturdy crystal chest. Diamondhead can also reflect energy blasts and throw them back at enemies. While his body is made up of one of the hardest materials in the universe, he can be cracked by sonic blasts. Watch out!

Diamondhead is in a majority of episodes in Season 1.