For easier study and organization gemstones have been grouped by the type. The main reason of grouping is that gemstones consist of varied list of substances.

Diamond and turquoise do not resemble each other but still they are considered as gemstones.

The Japanese pearl and the Sri Lankan moonstone can have the same features but the pearl don’t always belong to the gemstone.

Look through the major types of gemstones and their relation to each other. There are several types of gemstones and any gem may belong to more than one gem stone type.

1. Crystalline vs Amorphous gemstones
This type of gemstones is the most common. To the crystalline gemstones belong diamond and ruby because they are made up of a single crystal.

This crystal can consist of a single element (the carbon of diamond) or a chemical compound (the aluminum oxide of the ruby).

To the amorphous type belong such gemstones as turquoise.  These gemstones are created from a hardened mixture of other substances. While some elements of the mixture can be crystalline, the gem stone itself is not a single crystal.

2. Organic vs Inorganic gemstones
In most cases gemstones are made from non living materials. Such gemstones are called inorganic gems, for example Oxide (ruby, sapphire), beryl (emerald) and quartz (amethyst).

Orgainc gemstones are created from the living organisms which are formed from once living material changed over time into a stone.

For example, Amber is a typically clear, yellowish stone, which is formed from tree resin fossilized over years.

Jet, a form of coal, is a mineral which has been formed from decayed plant material under extreme pressure.

The other examples of the organic gemstones are pearl, ivory, and coral.

Some people believe that to be a true gem, the stone must be formed by gradual processes over long periods of time.

3. Mineral vs Rock gemstones
The type of gemstones can be determined by its content.

To mineral gemstones belong single, naturally occurring compound which are formed through various geological processes. Diamonds, rubies and jade also belong to this category.

Rock gemstones include a cohesive mixture of minerals. Lapis Lazuli is a great example of this gemstone type and is known as one of the first stones which can be considered as a gem.

4. Miscellaneous
Gemstones of this type can be blue vs. red; hard vs. soft; smooth vs. rough; opaque vs. clear.