Ajay
You have not given date, time, place of the native. As per your selection of yellow sapphire the native will enjoy Jupiter results. But Jupiter is in the star of Mercury who is badhaka to Pisces ascendant. If Rahu is behind ascendant degree, he will be in 12th which is not good.
Again consider the significations of Jupiter and Saturn.
If you are knowing astrology, kindly take into consideration all these things by casting a horoscope with correct details. Consider that planet which is a significator of 11th house (house of labha, fulfillment of desires).
Without knowing the correct position, don’t venture for stone selection, there are chances to throw the native into troubles. It is upto you.