@ Dibyendu Mandal,
Pearl is the gem for Moon and it should be worn on the little finger. This is the first choice. Secondly as it is friend of Guru/Jupiter it can be worn on the index finger and as it is friend of Sun, it can be worn on the third finger too.
Emerald (Budha/Mercury), people sugges wearing on the little finger, but I do not, s Mercury and Moon are enemies. Emerald can be worn on the Sun’s finger, next to the little finger or the middle (longest) finger. Never on the index finger (Jupiter) finger.
Wishing you good luck, may God bless you and above all?????
Cheers