What is Gemology?

Among gemological materials, we can include cut minerals (gems), some rocks, certain organic materials and artificial products.

Gemstones are defined as natural and inorganic substances with specific optical properties (color, transparency, shine…) and structural properties (hardness, thoughness…), and are usually rare.

They are formed in nature, without human intervention, and may be cut or treated in several ways.

Rocks are natural, solid and stable associations  of one or more minerals. Many of them have gemological interest, as such lapis lazuli, composed of haüyne, sodalite, nosean and lazurite; or unakite, a kind of granite with quartz, epidote and feldspar.

We can also consider in this group natural glass, like the different varieties of obsidian (pictured above), of volcanic origin; or impactites, formed as a result of the impact of a meteorite, being moldavite the most important example.

Some natural materials of organic origin might be of gemological interest, they can have animal origin (pearls, coral or carey, for instance) or vegetal provenance (like amber or jet).

Artificial products are also of gemological interest. This group includes reconstituted gems (made out of dust or gem pieces plus heat and pressure procedures) or composed (welding or gluing two or more pieces of diverse composition and properties).

Another example are synthetic gems, which have same composition, physical properties and structure as their natural analog. They shouldn’t be confused with artificial gemstones, which are human made but don’t have known natural analogs (cubic zirconia, for instance).

Finally, imitations are also artificial products that simulate the look of a gem or an organic natural material, but doesn’t have the same composition, physical properties and structure.