- Amorphous gems are composed of a very hard mixture of substances that have been suspended in solid form. Though amorphous gems may appear crystalline in appearance, they are not single crystals, but rather a collection of the carbon found in different crystals. Several examples of amorphous gem stones include opals, a sedimentary stone formed into gem stones, and turquoise, which is a greenish gem whose hue is further determined by the quantity of copper and iron in the mixture. Amorphous gems are one of the softer types of gem stones since they are not entirely solid.
- A crystalline gem is a gem stone that is composed of a solid crystal. This is the most common and expensive type of gem stone and includes stones like diamonds and rubies. These gems are composed of a single type of carbon that is specific to that kind of crystal. Diamonds, for instance, are composed of a hardened cubic carbon crystal and formed into an isometric shape. Because of this, crystalline gem stones are the hardest since they have no breaks in their crystalline structure.
- Organic gems are gem stones that are formed when a living organism becomes fossilized. For example, amber is a precious stone that formed as a result of tree sap being crystallized over a long period of time. It often contains the remnants of animals within the crystallization as well. Amber is both mined and found on sea shores as a result of erosion exposing large amounts of it under water. Another organic gem is coral, which is a result of fossilized and crystallized reefs under water.
- Synthetic gems are processed by man by manufacturing the chemical process that creates gem stones. Processes like flame fusion are used to cause the effects that the earth has on certain types of carbon to produce unnatural gem stones. Stones like this include cubic zirconium, which is a combination of different carbons being fused in a synthetic process.