Gemstones are precious mineral and rock formations that are extracted from within the earth and vary in terms of their size, color and structure. It is due to this diversity in their types that gemstones cannot be classified through a single classification system. There are many ways geologist classify rocks and minerals found. First way to classify gemstones is by categorizing them into natural, synthetic and imitated gems. Aside from that, they are also classified as organic or inorganic and crystalline or amorphous rocks.
Classification as Natural and Synthetic
The only difference between natural and synthetic gem is the way they are made. Natural stones occur naturally, in our geological system without any human interference in their formation. Natural gemstones are regarded as rare because no gemstone is same as the other. Each is formed under slightly different environmental conditions. It is this rarity that makes them precious and unique. To identify a real natural gemstone, one must look for inclusions in the stones as these gems are bound to have inclusions due to the addition of other minerals during the process of their formation.
On the other hands, synthetic gemstones are those, which are formed in labs by inducing the same environmental stimuli. Carbon and other chemical elements are used and treated under specific time, pressure and temperature setting to produce a gem. The gems produced in labs are chemically identical to those formed in earth.
Classification as Organic and Inorganic Rocks
Aside from classifying gemstones based on their occurrence, they can also be categorized into organic and inorganic gemstones.
Organic gemstones are those that are formed because of a living organism. It can include sea species, plants, shells, fossils, etc. The word ‘organic’ refers to something that involves organisms. Ivory, pearls, amber, coral, jet, ammonites, ammolites – they all are good examples of organic gemstones.
All other gemstones that are not formed through the organic way are categorized as inorganic. Whether they are found in earth, on its surface or beneath it, are known as inorganic minerals and comprise of almost all the gemstones we know of. Inorganic gemstones, which are created in labs, are not considered as gemstones, and that is why they cannot be advertised as such.
Classification as Crystalline and Amorphous Rocks
Gems can be classified in the manner of differentiation between amorphous rocks and crystallized rocks. Amorphous rocks are those, which do not have a particular crystalline structure. They are naturally occurring and often called mineraloids. Opal, amber and glass are all good examples of mineraloids. However, not all amorphous minerals are classified as gems.
On the other hand, crystallized minerals or crystals are those, which have a tight molecular structure with repetitive chains and formations. They are formed by three-dimensional arrangements of molecules. Diamonds and rubies are an example of crystals. Zircon is the world’s oldest found crystal. However, not all crystals can be classified as gems because crystals are pure substances that have a solid and definite structure, since their molecules are arranged in a specific three-dimensionally array.