Color is the most noticeable factor about gemstones. However, color alone is not the way gemstones are identified and categorized. All gemstones have a unique crystal structure and typical physical and optical properties.

 Natural, transparent gemstones are usually minerals. Minerals can be classified by species, variety and sometimes by group. 

A mineral species is defined by their common chemical compositions and crystal structures. Examples of mineral species include Beryl, Corundum and Quartz. Variety is a sub-division of species and is based on color, transparency or phenomenon (Asterism, Chatoyancy, Play of Color). Examples of mineral varieties include Emerald, Ruby and Citrine. A group consists of two or more mineral species that are similar in chemical composition, crystal structure and properties. Some gems are not minerals either because they are organic gemstones (pearls) or are not natural.  

Beryl

Emerald, Aquamarine, Morganite

Emerald is the most popular and well-known Beryl variety, followed by Aquamarine and Morganite. There are lesser-known varieties as well such as Heliodor (yellow), Maxixe (Blue) and Red Beryl.  

Corundum

Ruby, Sapphire

Ruby and Sapphire make up the corundum species and are one of the two most popular gemstones. Ruby is the red variety of Corundum whereas Sapphire comes in rainbow colors with Blue Sapphire being the most popular.  

Tourmaline

Tourmaline is one of the most commercially important gemstones and comes in a multitude of colors. Tourmaline comes in vibrant colors from rich reds to pastel pinks, intense greens, deep blues and vivid yellows. Paraiba tourmalines are copper bearing tourmalines and come in neon blues and green colors. They demand one of the highest per carat prices in gemstones.  

Garnet

Like Tourmaline, Garnet also belongs to the same mineral group with the same crystal structure but slightly different chemical compositions which gives it different colors. The most important Garnet species in gemstones are: Pyrope, Almandine, Spessartine, Grossular and Andradite. Some examples of Garnet varieties include: 

Opal

Opals are known for their inspiring play of colors which occurs due to the interaction of white light with their orderly internal molecule structure. Opals come in many types and are categorized by their background (body color) color. Common opal types are Black opals, White Opals, Water Opals, Fire Opals and Boulder Opals.  

Tanzanite

Tanzanite was first discovered in 1967 by a Masai Tribesmen in Merelani Hills, Tanzania. Its name was given by Tiffany and Co., inspired by the country it was discovered in. Since its discovery and heavy promotion, Tanzanite has become one of the most popular gemstones.

Spinel

Historically many gemstones had been misidentified as Rubies however were later on recognized as Spinel. Spinel comes in variety of colors from reds, pinks to shades of purple, blue and bluish green.  

ChrYsoberyl

Alexandrite, Cat's Eye ChrYsoberyl

Alexandrites and Cat’s Eye Chrysoberyl are two of the most rare and popular phenomenal varieties of the Chrysoberyl species. Alexandrites are known for their color-changing phenomenon whereas Cat’s Eye Chrysoberyl display spectacular chatoyancy (cat’s eye).  

Jadeite

Jadeite has been a treasured gemstone for thousands of years especially in Asia. Jade comes in a variety of colors however green is the most popular and valuable.  

Organic Gems

Coral, Pearl

Organic gemstones are gemstones that are derived from living matter I.e., from plants or animals. Examples include Pearl and Coral. As organic gems are derived from plants or animals, environmental concerns led to a global treaty called CITES. Its purpose was to protect the environment from unregulated trade.