I have the same problem that you have.
In vedic astrology Emerald is my most important gem.
In the "anukul" system of choice the best thing to do is to use gems that are associated with planets that are well positioned in the astological chart, and one of this planets for me is Mercury.
Very often the rules of Jyotish gemology say that one have to wear a gem all time long, without any break.
But Emerald is a very strong gem, in my opinion not very good for night time, because it is calming, but too active at a mental level, useful for the study, and it is not good for winter too, because it has a very cooling effect.
Moreover, it contains beryllium, that is a very powerful element, and a poison; I suppose that when a body have contact with beryllium in a gem, it can act in a homeopathic way, for example helping to soothe allergies, because the immunitary system react in a positive way to the presence of a poison in a very low quantity.
In conclusion, I use Emerald only during my personal Mercury dashas, or planetary periods, but never continuosly. Ciao!