Throughout the breakdown, I preview renders where color is important with the film look applied, and renders where brightness value is important (mix factors) without it.
The ray depth hack especially really helps brighten up glass in any Cycles scene. Note: throughout the breakdown, there are nodes with excess outputs hidden with Ctrl+H, which is why they don't all show up.
I'm using the surface version of absorption instead of volumetric, mostly because I didn't want get two separate layers of volume shader working together, not when a node group like this renders so much faster
The idea is that the 3d procedural texture will effect the absorption in 3d space. Not sure that's what's happening though.
I use Lerp as an inexpensive alternative to MixRGB when I just want to blend two grayscale passes. I use Remap more to set the range for roughness, bump strength, and other simple gradients. They're the same operation.
The SSS looks so much brighter now than it did on its own because the transparent materials above it are letting much more light shine through. I spent most of the time on this layer looking at it already mixed in, the difference is so big.
I'm actually using RGB values of 1.1 for the volume, to give it a little extra pop
Node tree overview
Readable version Q1
Readable version Q2
Readable version Q3
Readable version Q4
Breakdown of the shader/texture nodetree on my gemstone render: https://www.artstation.com/artwork/V0KKZ