There is no "gamma" node, just the value in the image settings and in the render settings. 

I've tried to rebuild your shader (what are the values for wave and were do the math nodes go there?) and it looks like this, rendered with GC. One light and a skydome with the image of a grey room loaded, RDNA's infinity cove in the background. Your material is very bright. Does that look bad to you? I still don't know why your material looks that crappy in the render above. 

Your shader will need a reflection node too if you work with IDL. Indirect light does not trigger specular nodes, you need low level reflection for that. 

A ship in port is safe; but that is not what ships are built for.
Sail out to sea and do new things.
-"Amazing Grace" Hopper

Avatar image of me done by Chidori.