Navratna Jyotish (Graha Ratna)
The astrological Vedic text "Graha-Gocara-Jyautisha" gives detailed instructions on how natural gems can be fashioned into powerful jewelry, that attract good fortune and have a positive effect on the wearer.
These planetary jewelry are called "Kavacas", or Jyotish Talismans.
The astrological powers of gemstones are derived from the special cosmic influences of their associated ruling planets.