Should Yellow Sapphire be Worn in Index Finger ? (Kya Pukhraj ko Tarjani Ungli Mein Pahanana Chahiye ?)

I am sure your answer to this question would be "Yes". Because most of the astrologers suggest yellow sapphire to be worn on the index finger. 






Let me ask you two questions now:

1) At the time of havan while offering havan samagri in auspicious fire do you use index finger ?

2) While reciting mantra with the help of a japa mala(rosary), do you allow your index finger to even touch the