If someone has Retrograde Jupiter with 28.41 degree & Rahu with 6.28 degree in 1st house (in Pisces sign) of pisces ascendant, then will wearing a yellow sapphire / topaz be helpful or not? Is kendrapathi dish or Guru- Chandan yog is formed.
You did not mention where Chandra is.
Though there is a distance of 22 degrees between Guru
and rahu ,there is Guru rahu yoga.But bad effect is minimum
as the distance between them is 22degrees.
You can use colour ray method of Sun light,instead of using
yellow saphire. firstname.lastname@example.org
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.
In theory along with considerations Mr. JVS Rao mentioned, its important to take into account purpose for wearing stone as well (health, mental peace, career or marriage).
Practical experience says that wearing stone is more from optics point of view and it cannot replace hard-work, meditation and self discipline. Otherwise everyone could wear stones and improve their situation (job/marriage/education) which is not the case.
God Bless you with logic and rationality,