Quote - The only render engine I know of that can accurately render diamonds (including light dispersion) is Maxwell Render by Next Limit Technologies. Worth taking a look in their gallery,

 

accually many render engines can do gems, i mainly use carrara5, and does it quite well. the tools in most of the 3d apps contain the tools to do most everything, it's just a matter of simplicity. Poser i am sure would be capable of doing caustics if someone was bored enough to sit in mat room for 3 months and figure out the 1000+ nodes in the right order :) carrara5 however has that built in already, but does not take into account the "prism" effect when determining colors. it does however have the tools needed to program a plugin to do it, and much more simply. so the question is not of capability, but rather simplicity and value of doing it.