The remedies are Rahu and Ketu remedies: mantra, eclipse-day practice, and charity to those the two nodes signify. Gemstones for either node are withheld in most charts, which makes this one of the clearest cases where mantra and daan are the whole answer.
Kaal Sarp Dosha is the pattern where every planet falls between Rahu and Ketu. It is a modern classification rather than a classical one, and its reputation for calamity outruns anything the older texts claim for it.
The mantra, the weekday fast and the charity are safe for anyone — they address Rahu without amplifying it. Hessonite Garnet 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 Rahu all belong to that day.