left: model reference
light brown eyes
right: pose reference (he should hold his sword much lower to display the uniform)
Coat, Shoulder armor, helmet
left: I like Ulquiorra's silhouette for the coat.
A long coat but the front ends at the waist. It should be red.
Clements wears the fragment of a demon's skull as a helmet. Similar to the Arrancars.
right: the right and left shoulder armor meets at the chest to form a cross over the chest/torso.
His shoulder armor is also carved from demon bones, like his helmet
For the demon bone's that make up the shoulder armor/cross and helmet, I'm thinking gold.
Front panel pants
just a crisp clean look. Black or dark gray.