Mr. Arun
Don’t go by the astrologers’ views in the net. There is no such idea that for every month there would be one gem stone. Gem stone is suggested based on the strength of planets in the birth chart that to in bhava chart. The game is played by certain astrologers to encash the weakness of the public and gain money. They are purely commercial to sell their products. They tell in such a way that they are different to others and attract the innocent people.
If you provide your date of birth, accurate time of birth and place of birth, the stalwarts in Vedic astrology like Navneet Khanna jee, TKC sir and others in this forum will suggest you. As this is a free forum you can get guidance.
In KP system, I will suggest the stone which is suitable to you. It is your choice.
Good Luck
JVS Rao (KP system follower)