反光铜染料 is a type of 染料 that is randomly given to you when you give a 奇异植物 to the 染料商 NPC. When equipped, it will give the selected accessory/armor a copper-plated, "shiny" effect, reflecting the surrounding light around the player. The reflection is more pronounced the closer the player is to a light source. The dye will prioritize light from the sun when the player is outside. From some perspectives, the player may look 3D when this dye is equipped all over.
As with other reflective dyes, this dye is not animated when standing still, but the shading on a dyed piece of equipment will change according to the surrounding light, giving it the appearance of light reflecting off of a shining metallic object.