![[a set of minerals]](graphics/gmfw_b.jpg)
There are over 2000 minerals in the world. Out of these 2000 approximately 90 are classified as gem material and only 20 or so, are used in the jewelry trade.
To be classified as a gem, a material must have certain characteristics:
These characteristics are described in futher detail at Colored Gem Site
A good definition of each of the major gemstones can be found at the International Gold and Gems Site
