PRECIOUS STONES

Gem-stone or a precious stone is a highly attractive piece of mineral. But certain organic compounds are also considered as gem stones.

E.g.: Amber

After cutting and polishing gem stones/precious stones are used in jewelry.

Gemstones/precious stones fall into different categories because of the composition.

E.g.: Diamonds-Made of carbon

Rubies-Aluminum oxide

Many gems are crystals and classified using a crystal system

E.g.: cubic, trogon, monoclinic

Classification of gem stones/precious stones

Gems/precious stones are classified classified into different groups, species and varieties.

E.g.: ruby is the red variety of species corundum

Other colours of corundum - sapphire

Value of the gems/precious stones

Value of a gem depends on the refractive index, dispersion, specific gravity, hardness, cleavage, fracture and luster. Value of a certain gem changes from the country to country. Coloured gem stones are prized specially for its great beauty and aesthetics.

Processing

Most of the gems are cut and polished before they fit into a particular purpose. Some gems are treated to increase their beauty and some of the non-gem stones are converted to gems by treating.

Methods of gem treating are,

Heating

Irradiation

Waxing/Oiling

Fracture filling

Some gems are synthesized artificially

E.g.: Cubic zirconia

Synthetic corundums