I have been playing a bit with this lately and i have learned quite a lot in the process about reflections and refractions (maps, limits, etc). How to make rendering more efficient to achieve good results and a bunch of other stuff...this last render only took 5 mins with Mental Ray and FG/HDRI on. Learned tons of tricks. Anyways, I am pretty happy with this. Just as an FYI there is an outer crystal, an inner crystal, the liquid material and the tubing. All transparent.