| Gems are also called as precious or semi-precious | | | | the crystal system that describes crystal |
| stone that is cut, polished and re sized to make | | | | properties is cubic, trigonal, monoclinic, hexagonal |
| use by jewelers for ornaments or other purpose. | | | | and orthorhombic. |
| It is a natural occurrence beneath the earth with | | | | Optical characteristic of gemstone are considered. |
| unique attraction, chemical composition, crystal | | | | The optical characteristic is primarily derived from |
| system and durability. Most of the gems are hard, | | | | chemical composition and crystal structure. Color, |
| but some stones are soft and tough. Usually, it is | | | | optic character, refractive index, birefringence, |
| made of minerals that encompass high degree of | | | | dispersion, fluorescence, phosphorescence and |
| beauty, rarity, durability and desirability. A | | | | clarity are some of the optical characteristic of |
| gemstone is highly graded for its beauty and | | | | the stone. |
| appearance. Properties that determine the value | | | | Next, gemstones are characterized by the |
| and beauty of a stone are color, clarity, cut, carat | | | | feature called specific gravity. Generally, |
| and rarity. Gems are available in different shapes, | | | | gemstones adversely differ in their density. |
| sizes, cut, color and clarity. Gemstones has unique | | | | Gemologist refers to specific gravity or relative |
| characteristic that is classified by gemologist in | | | | density, the ratio of density of the gemstone. |
| different specifications. Traditionally, gems are | | | | Durability, the hardness and toughness of the |
| classified in different method, but today gems are | | | | stone. Lastly, gemstones are characterized by |
| classified by gemologist by the technical | | | | their durability. Durability refers to hardness and |
| terminology specified to the field of gemology. | | | | toughness which in-turn refers to resistance to |
| Traditionally, gemstones are classified as precious | | | | scratches or piercing and resistance to breakage. |
| and semi precious gemstones. Diamond, ruby, | | | | Diamond is the hardest and toughest gemstone |
| sapphire and emerald are precious stones and | | | | that is resistant to scratches and breakage. |
| others are semi precious. Today, huge number of | | | | Also, it is characterized in terms of refractive |
| stones are available and they are identified by | | | | index, dispersion, specific gravity, hardness, |
| gemologist by their characteristics. In modern | | | | cleavage, fracture, and luster. |
| times, gemologists identify gemstones by their | | | | Stones are classified into different groups, |
| characteristics and the technical terminology | | | | varieties and species. For instance, ruby is a |
| specified for the gem. Physical characteristic that | | | | variety of red and corundum species. While |
| makes a gem valuable are color, clarity, cut, | | | | emerald, aquamarine, morganite comes in the |
| unusual optical phenomena. | | | | species beryl. |
| Gemologists characterize gemstones in different | | | | Even gemstones are classified as natural or |
| terminology. Firstly, chemical composition of the | | | | synthetic. Synthetic are created in laboratories |
| stone is identified i.e. diamond - C and Amethyst - | | | | under specific conditions, while natural will have |
| SiO2. Secondly, the crystal properties are | | | | imperfections due to the uncontrolled growth |
| ascertained using the crystal system. Some of | | | | condition in nature. |