Help with visor from an armor, needs to bright and relfex like a rainbow

Hi people, Im new here, and I model in Blender and texturize in Photoshop, u can see that white visor in the helmet of the armor

I was working with Bumped diffuse texture slots till now, in Photoshop I make the diff map, then create an alpha channel and paste there the emite map to create the Illumin (A) slot, same with the spec map, I paste it in an alpha channel of the diff map in order to create the Base (rgb) Gloss (a) slot, and a respective height map, which I use it in crazybump to create the Normalmap, as I saw in cg coockies tuts, all works fine

but now I need that visor must bright and reflect like a rainbow, like this example

I dont know if what I made in Photoshop is fine, this is the diff, the selected pixels are the visor, I think that should be transparent in Photoshop or in Unity? It must be made in another uv map? what size it can be 512*512? In Unity I must use another slots for only this visors? which ones? Should I make changes in my Spec map?

Need ur aid, thxxxx :yes: