I have the same problem.
There's however a setting in trinity for this. Although i have checked gems to be looted, the bot never pick up any.
Does anyone have an idea why ?
Edit:
i found a solution:
In trinity settings where you check where you pick or leave gems behind, there's a little menu of what quality of gems you should pick or leave. Mine was empty, so when i changed to marquise+
my toon started picking gems again.