The Rahu beeja mantra is "Om Bhram Bhreem Bhraum Sah Rahave Namah". The classical count is 18,000 repetitions, built up over weeks from one mala of 108 a day, and Saturday is its day.
Mantra is the safest of the classical remedies: it can be started today, costs nothing, and cannot be worn against the chart the way a stone can. The Sankhya — the prescribed number of repetitions — is completed over weeks, beginning with one mala of 108 a day and building up. Sincerity matters more than arithmetic.
The Rahu mantra is chanted on Saturday, and most powerfully during an eclipse; the Durga Saptashati is used for the same afflictions.
An afflicted Rahu shows as anxiety, addiction, scandal and chasing what recedes as you approach it. Durga and Bhairava worship, and eclipse-day practice, are the classical response.
The classical Sankhya is 18,000 repetitions, completed over weeks rather than at once. Begin with one mala — 108 — a day and build up; sincerity matters more than arithmetic.
Saturday. Fasting, charity and mantra japa for Rahu all belong to that day.
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.