Cycles is not rendering caustics, even though "No Caustics" is disabled? I am having difficulties with the Glass shader because there are no caustics and the shadows that show up in the glass shaded object look as if they are blobs of ink.
I do have the 'No Caustics' option disabled, and from the research I've done, this one checkbox is the only one that people seem to be mentioning when it comes to caustics.  

Does anyone have advice on how to deal with this issue?  Here's a screen capture of the scene setup that I'm working on.
Lamps (with the exception of mesh lamps) will not cast caustics if they don't have Multiple Importance Sampling enabled on them.

Make sure any lamps in your scene have this enabled: