SEMI PRECIOUS GEMSTONE ( उपरत्न )
Gems may be described as minerals or organic matter used for personal adornment or investments. Besides a few exceptions like ivory, pearls, coral and amber ; all gemstones are minerals. 

They Are Affordable.

Astrological uses of gemstone- Wearing gemstones help in diminishing the inauspicious effect of the planets. Each planet is determined by a specific gemstone and worn after carefully examining a person's horoscope.