A Vial of Prismatic Dye

Vials of prismatic dye are necessary to have in a character's inventory in order to dye your armor.

The vials are available for free from the Fighters Vendor in the Fighter's Guild.

To dye armor, open your inventory, and click "Dye" - then change the color by clicking the color swatches on the right column. Each piece of armor that is modified in any way will consume a single vial of prismatic dye.