different types of gems
Alternately types of gemstones may be classed by how they are made. Another way to classify gems is by describing them as precious, semi-precious or organic. When gemstones are identified by category, the following categories may apply: 1  Diamonds â considered the most precious stone in the world.
Peridot Peridot is the gem variety of olivine. Derived from the mantle and rarely from meteorites. Spinel Spinel The gemstone that was confused with ruby and sapphire for over 1000 years. Organic Gems Organic Gems are gems formed from or by plants or animals.