It is interesting to study the origin of gems and their discovery,
which makes a fascinating story.
Gemstones
are actually minerals found in rocks with a certain quality and
intrinsic value. When rocks (igneous metamorphic or sedimentary)
change due to the intense heat and pressure within the earth, new
rocks with minerals are formed which often have gemstones in them.
There are a hundred different types of gems found on the earth's
surface. They are classified depending upon their clarity and their
chemical characteristics.
Specific types of gems are associated with specific rock types. To
be specific, the sources of colored gems are in sedimentary
deposits, such as gravel beds, while marbles and some other types of
gems are found in metamorphic rocks. They are then cut, polished and
fashioned to make jewelry or other adornments. The brilliant colors
of the gemstones are due to the metallic ions in the composition of
the gems.
However there are certain rocks that are not minerals yet considered
to be gemstones, such as lapis-lazuli, Amber or Jet.
Over the years
gemstones
have been classified as precious and semi precious. Primarily
diamond, ruby, sapphires, emerald are considered precious. Over the
years pearl, opal and amethyst have been included in the "precious"
category, and the others such as Jade, Onyx, Agate, and Turquoise
are semi precious. There are of course a hundred other varieties.
There are Organic gems too, formed from plants and animals. Pearls
are formed inside the freshwater shell fish when irritants get
inside them. Coral is formed from skeletons of marine animals. Amber
is made from fossilised tree resin, and Jet is fossilised wood.
Imitation gemstones are also available in plenty now, which look
like the original but have neither their chemical nor physical
characteristics. There are various processes to check the
authenticity of the gems, which help in recognizing their worth.
Most commonly - the four C's (color, cut, clarity and carat). This
was basically introduced for the customer, to understand the quality
of the gems.
Whatever the origins, Gems are prized possessions - and has been for
centuries.