A stone precious (also called gem, fine gem, jewel, stone or semi - precious stone precious) is a piece of mineral glass, cut and polished as is used to make jewelry or other adornments. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another characteristic that gives a gemstone value.
The traditional classification in the West, dating back to the ancient Greeks, begins with a distinction between precious and semi-precious; Similar distinctions are made in other cultures. In modern usage, gemstones are diamond, ruby, sapphire, and emerald, and all other gemstones are semi-precious. This distinction reflects the rarity of the respective stones in antiquity, as well as their quality: they are all translucent with beautiful colors in their purest forms, with the exception of colorless diamond, and very hard, with hardnesses of 8 to 10 on the scale of Mohs.
Other stones are classified by their color, translucency, and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets are relatively cheap, a green garnet called tsavorite can be much more valuable than a medium quality emerald. Another unscientific term for semi-precious gems used in art history and archeology is hard stone. The use of the terms "precious" and "semi-precious" in a commercial context is undoubtedly misleading as it misleadingly implies that certain stones are inherently more valuable than others, which is not necessarily the case.
In modern times, gemstones are identified by gemologists, who describe gemstones and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition. For example, diamonds are made of carbon and aluminum oxide rubies.
Gemstones are classified into different groups, species, and varieties. For example, ruby is the red variety of the corundum species, while any other color of corundum is considered sapphire. Other examples are emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow), and morganite (pink), which are all varieties of the mineral species beryl.
