I agree with anm767.
Each daily quest gives 15 stones and you can complete illusion daily quest 15 times per day as well.
That way you get a lot of stones.
But yea, the drop rate of the refine boxes feels way too low compared to that.
Not sure if possible, but maybe adding refine boxes as additional reward for the quests would help? (Maybe not on all 15, but every 3rd or 5th? But that might be too complex)