The world of gemstones offers an endless choice of colour and variety for jewellery-making and the science and history of gemstones in itself is fascinating.  The history of gemstones goes back for centuries since they were prized long before the discovery of diamonds.  Many prospectors in the past have risked their lives to find them even till present day.  Although mining conditions in some areas have improved, people continue to put their lives at risk in search for the most beautiful, naturally created specimens from earth.

What are Natural Gemstones?

Natural gemstones are naturally occurring stones formed from minerals.  A mineral is defined as a solid crystalline chemical element or compound that results from the inorganic process of nature and that has a characteristic crystal structure and chemical composition or range of compositions.

Characteristics of Gemstones

Within the mineral kingdom, the most common characteristics of gemstones are their chemical composition and crystal structure.  The combination of these characteristics, together with the physical and optical properties are the most important in their identification.  All minerals that have identical chemical composition (or a range of compositions) and identical crystal structure are considered to be of the same Species.

There are more than 3500 known species to date and this number is increasing each year but only a very small proportion of these minerals have the attributes which qualify them as gemstones: Beauty, Durability and Rarity.

Gemstones Species

For example, Quartz has the chemical composition of SiO2 (known as silica) and a hexagonal crystal structure.  It is one of the most common minerals.  It is part of many common rocks including granite, but also forms in varieties classified as gems:

Quartz varietiesVariety Amethyst: Blueish-Purple to Purple to Reddish-Purple

Variety Citrine: Yellow to Orange to Brownish-Orange

Some other quartz varieties include: Rock-Crystal, Tiger’s Eye, Aventurine, Smokey

Corundum is another well known species with many varieties including Sapphire and Ruby.  Different varieties of corundum have dramatically different prices!  Factors that affect a gem’s value include:

Colour, Clarity, Cut and Carat Weight

Read more about the 4 C’s in my next post.

 

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