Let's say there's this object...

How do I make it shine in various colors depending on angle of view / angle of the light that shines over it?
The object needs to shine in 4 colors and change into them gradually: yellow-green-blue-indigo and go black when no light shines over it.
This isn't about setting color changes recorded to the timeline though, as it should be light-based. The object will be exposed to light from various angles and change reflected color according to the light's position / viewing angle.

Can someone explain how to do that, please? I am trying to emulate fish scales, specifically those of black swordtails.