Most people know the world of gemstones as comprised of precious gems and semi-precious gems. The precious gems include diamond, ruby, sapphire and emerald; and semi-precious gems includes the more common stones such as amethyst, topaz and garnet. But the world of gems is much richer than this simplified picture.
There are actually more than 100 different varieties of gemstones. Many are rare and exotic, but the internet has made it possible to find gem dealers who trade in many rare varieties.
What's behind the growing interest in rare and exotic gems? It is not just gemstone collectors who are looking for the rare and unusual. Jewelry designers are discovering new colors and textures to incorporate in their designs, and consumers are eager for information about the lesser-known stones. Miners now understand there is a market for these stones, and material that was once ignored is now carefully collected and graded.
Some of the new gem types are not exactly new. Some, like prehnite, apatite and sphene, have been known for years, but haven't been used much in jewelry because they were too soft. But jewelry designers have realized these stones are actually more durable than perennial favorites like opal, and when properly set in earrings or pendants they will last for many years.
Other gems in the lesser-known category are actually very durable and are suitable even for rings. Many of them -- such as chrysoprase, dendritic agate, rutilated quartz and fire agate -- are members of the quartz family and have very good hardness and no cleavage.
Many of the lesser-known gems are relatively inexpensive. That makes them economically attractive for jewelry designers. But like so many gemstones, supplies are variable and uncertain. You will not find every different kind of gemstone available in the market at any given time. The precious gems can always be found, but many semi-precious stones, such as demantoid garnet and alexandrite, are actually rarer than diamond or ruby.