@ Anirban
Mercury is the lord of your ascendant. Ascendant signifies body, its immune and general health conditions. Malefic planets in ascendant or weak ascendant lord reduces ones physical well being in general. In such cases, it is advised to wear the ascendant lord, in your case Budha (Emerald).
The same will support career as it is the lord of the 10th house of Karma and career too.
Wishing you good luck, may God bless you and above all?
Cheers