When I account for each gem change it suggests, it just doesn't seem to be a big enough difference to spend the gold on changing that many gems.
The total increase for changing the gems that rawr suggests to maximize the dps would be 61.1. Like I said, that just doesn't seem worth it. She would have to change out 12 gems to do this, which is, roughly, 1,200 gold or so.
Don't be such a cheapskate...get farming.