I experimented a little with adding a parti_Volume thinking that the ice really is volumetric.  It made a really cool darkening effect, but render times shot through the roof.  I went back and tweaked the cloud shader driving the translucency to clear the ice up a bit and render times dropped to a manageable 30 seconds.

Just to check on the darkening I switched the background to red.  Any of the splotchiness is from using only 100 fg rays.

Essentially the little fuzzies inside ice cubes are formed by tiny bubbles.  So why not just emit some particles?

That’s 100 particles rendered at 26 seconds.

500 Particles rendered at 44 seconds

And that’s 1000 particles rendered at 1:07

To get a truly fuzzy effect this way would shoot through the roof.  But then it occured to me to try some other particle types.  This one is a MultiPoint, set at 1000. :56 to render.

Getting the gray out was a pain.  This last example uses MultiStreak.

Feeling good about all these options for different looks.