you'd need caustics and dispersion enabled. (Dispersion is where you'd set the abbe number.) You'll want to use spot lights (NOT area lights) for more effective caustics. (Area lights are too diffuse.)
i only turned on dispersion. guess i need to turn on the caustics in the option menu to make it work. thanks for the reply. will post results if i succeed it.
There been some suspects that if both vray for SU and Thea for SU are installed there is change for a crash (maybe observers do not play well). Anyhow... about the crash, you really should post a detailed bug report at Thea forums (if you not already have done so); used software version (su, thea & vray..., os, hardware specks, gpu drivers and so) so that Tomasz can take a look on this. http://www.thearender.com/forum/viewforum.php?f=82
Keep in mind that deleting components does not remove them from the file. The components will still be held in the model. Any materials you might have tried remain in the In Model Materials collection as do Styles. Go to Window>Model Info>Statistics and hit Purge Unused to get rid of the unused stuff.
Although not required, I like to use a plugin made by TIG to purge unused stuff because it gives a report of how many of each sort of thing gets purged.
The native move toll will do that also. If you start move and then input [x,y,z] it will move absolute, <x,y,z> is locale relative move, [,,z] you keep x,y same and move in z , etc