Gemstone Identification

Gemstone grading and identification used to be performed by close examination by human eyes. It was one of the most conventional methods used as in those days. Nowadays there are many highly equipped scientific labs all over the world where precious gemstones are tested scientifically for their genuineness. There are various tests that are conducted to identify a gemstone. The first test applied for identification of gemstone is hardness. Gemstones are tested for their purity by testing their respective hardness. Based on the hardness value, the genuineness of the gem is tested.

Another important way to identify and test gemstone is called crystal morphology. The crystal structure is also one of the vital tests to know the purity of the gemstone. The entire pattern of the crystal is observed carefully and is matched with the standard crystal pattern. The shape of crystal depicts the symmetry of crystal and its atomic arrangement. It is tested whether it is octahedral prism or a hexagonal prism based on the atomic order.

One of the principle determinants to identify gemstone is, its “color”. By observing the color of the gem, it is tested for its purity. Though it is highly unreliable method but is still used.

Specific gravity is another factor to identify a gemstone. Specific gravity is measured as:

Comparison of weight of gemstone in the air to the weight of gemstone immersed in the water equals the mass per volume. The specific gravity differs with structure of crystal and the chemical composition.

Refractive index is also used to identify a gemstone. Refractive index is determined by refractometer. Critical angle is also determined to find out the refractive index. Total internal reflection occurs at critical angle.

One of the widely used methods to identify the gem is Dispersion. Various other optical properties are also used to identify a gem. Based on the optical behavior, gems are categorized into various groups and it becomes easy to identify them by just observing the optical behavior