Gemstones are classified into two categories, Precious and Semi-Precious, on the basis of their characteristics.
• Precious Stones
Gemstones which are highly valuable for their hardness and rarity, are known as Precious Stones. Precious Stones are generally expensive in comparison of Semi-Precious Stones. Precious stones include Diamonds, Emeralds, Rubies, and Sapphires.
• Semi-Precious Stones
Gemstones those are valued for their beauty and not covered under any one of the four ‘Precious Stones’, are known as Semi-Precious Stones. Semi-Precious Stones are available in all price ranges from low priced to high priced. Semi-Precious stones are Alexandrite, Amethyst, Aquamarine, Citrine, Garnet, Iolite, Onyx, Opal, Pearl, Peridot, Tanzanite, Topaz, Tourmaline etc.