Diamondhead is a silicon-based life form. His body is composed of durable pale green crystals. He sports two crystal shards on his back and has a sharp point on his head. He wears a uniform which is black with a yellow "V" stripe on the middle of his torso.
In Don't Laze Me, Bro, Diamondhead grew the crystal formation on his head so that it resembled a pompadour and wore a red bandanna around it. His outfit was also decorated with three yellow upside down triangles forming a vertical fast forward symbol on each side of his legs.
In Ye Olde Laser Duel, Diamondhead wore a green vest with blue orbs on his chest and shoulders over his regular uniform, as well as a fake brown mustache.
Diamondhead wears the Omnitrix symbol on his chest.
Diamondhead in Don't Laze Me, Bro