According to Indian Astrology there are 84 gemstones. Among them the nine precious stones of Ruby, Pearl, Yellow Sapphire, Diamond, Emerald, Blue Sapphire, Red Coral, Hessonite Garnet and Cat’s Eye or Cymophane have been awarded distinct status. These are called the NavRatnas. The other stones are semi-procious stones. But some of the semi-procious stones are most powerful and they should not be considered as inferior to Nav-Ratnas. In hardness, Iustre, clarity and radiation some of the semi-precious stones work immensely.
Unlike precious stones there are 19 semi-precious stones which work effectively and as the substitutes for the precious stones.
The 19 semi-precious gemstones identified in this respect are Turquoise, peridot, Tourmaline, Topa, Ametyst, Rock Crystal, Moonstone, Garnet, Neeli (substiture for blue sapphire), Aqumarine, Jade, Bloodstone, Lapis-Lazuili, Amber, Agate, Malchite, Jaichint (orange colour stone for ratio), Green onyx and Green Bery1.
Now a days many stones are manufactured through artificial processes and are available in the market. Although artificial gems look like the precious and semi-precious gems they have no power at all. They cannot do any benefit to the wearer. Only a “Gemmologist would be able to find the different while ordinary person is unable to detect this.