Gemstones are mineral crystals or organic materials that have been cut and polished into beautiful items by skilled craftsmen. The minerals are naturally formed, solid, inorganic chemical compounds found in rocks. Each mineral has a fixed chemical composition and regular atomic structure, which gives it the specific hardness and color it possesses. Many natural crystals are attractive enough to be displayed. However, most of these crystals are faceted and polished to enhance their appearance.

Few gems, which are called organics, come from plants and animals. These gems include ivory, amber and pearl. There is a category of gemstones known as synthetics. They do not have any natural origin and are produce in laboratories. These artificial gems are cut to resemble the real ones. They have the same physical properties and chemical composition with natural gemstones. Gemstones are, typically, measured by their weight in carats.

To be considered a gemstone, it has to be rare, beautiful and durable. Gemstones, in its natural crystalline form, are rare, which means that they could only be found in certain parts of the world. Their scarcity makes them valuable in the market. The color of the minerals must be attractive, so that the gemstones will appear beautiful. Gemstones must be durable, which means that they should be hard enough to withstand scratches and damage.

The most valuable characteristic of gemstones is the color. Colorful gemstones such as emeralds, rubies and sapphires are highly priced. Diamonds, though colorless, are made beautiful and brilliant by skillful forms of cutting. White light is made up of a combination of the spectrum of colors. When white light falls on a gemstone, some of the colors are absorbed while the rest are reflected back. Those colors that are reflected are what we see as color of the gemstone. As each mineral interacts with light differently, a wide variety of colors of gemstones is produced.

The physical properties of gemstones are their hardness, their specific gravity, and the way they break. These properties depend largely on the atomic structure and the chemical bonding of the stone. The hardness of a gemstone is measured by how well it resists scratching. The specific gravity or density of a gemstone is derived by assessing its weight base on the weight of an equal volume of water. Gemstones can break in two ways, either by cleaving or fracture. The way they break depends on the atomic structure of the stone. Gemstones that cleave will break along the planes of weak atomic bonding. Those that fracture will break along a surface which has no relation to its atomic structure.