Quote - Lurex is a fabric which has reflective metal fibers woven in, which causes it to change color at different angles and in different light, as well as look "sparkly".  I have done my best to recreate it.  Doing so for GC hasn't worked so far.  Why?  Who knows?  I don't.  The experts are strangely silent, when I bring up the topic.  Could it be that Firefly and GC have limitations we don't like to discuss?  Maybe?  I speculate, perhaps unfairly.  Ahem.

There is no big secret to gamma correction, it's not black magic. What it does is, it takes the output pixels of a render and applies an exponent of 1/gamma (typically, 1/2.2) to the r, g, and b channels. To texture maps, it applies the exponent of gamma (2.2) to the r,g and b channels of each pixel. 

That's it.

Gamma correction makes renders look different. It's intended to make them look different, if renders looked the same with or without gamma correction, gamma correction would be doing nothing.

There are no shaders that are somehow incompatible or limited, there are only shaders that were built to look good on a system without gamma correction and then don't look good when used with gamma correction.