Saturn does not accept substitutes for the work. The classical response is Saturday service to elders and labourers, the Shani Stotra, restraint in food on Saturdays, and Hanuman worship — the deity classically able to pacify Shani.
Sade Sati is the seven-and-a-half years Saturn spends transiting the twelfth, first and second houses from your natal Moon. It is not a dosha — it is a transit everyone lives through roughly three times, and its difficulty depends on where Saturn sits in the birth chart.
The mantra, the weekday fast and the charity are safe for anyone — they address Saturn without amplifying it. Blue Sapphire is not: a planetary gem strengthens whatever the graha is already doing, so it needs a chart reading first.
Saturday. Fasting, charity and mantra japa for Saturn all belong to that day.