Diamond rings, opal bracelets and pearl earrings all contain gemstones. The exact definition of a gemstone includes minerals, rocks or organic material that can all be used for ornamentation, art or jewelry. A gem is a type of gemstone—a diamond, for example—that must be cut and polished for its true beauty and brilliance to show. In contrast, gemstones such as pearls and opals require no extra polishing, making them different from gems.
Where do gemstones come from?
Gemstones are found all over the world. Some, such as diamonds, are mined from deep underground, while others like tourmaline are found in streams, and are the result of years of erosion in the surrounding rock. Garnet is normally found imbedded in a certain rock called gneiss, which at one time was subjected to high temperatures.
How are gemstones defined?
All minerals, of which gemstones are a part, are defined by their specific gravity, their hardness and their color. Specific gravity is defined as the measure of a mineral’s weight when compared to the same volume of water. Gemstone engagement rings must be hard, so hardness is another factor used to define minerals. Gemologists use what is called the “Mohs scale” when defining the hardness; within this scale, the softest mineral is talc and has a rating of 1, and the hardest mineral is a diamond, which has a rating of 10. All gemstones are defined by color, which allows for quick identification but not great accuracy. For example, defining a turquoise as “blue-green” is helpful, but not definitive.
Gemstone formation
Gemstones are formed in a number of ways, and the color or colors found within each stone are the result of their chemical makeup during the formation process. Turquoise, often used in gemstone engagement rings in the southwestern part of the country, is formed when water courses through rock which contains copper, aluminum and phosphorus. Lapis is technically a type of rock and not a gemstone, yet it is still used for jewelry. It is formed when magma deep within the earth forces its way into another rock, where the magma melts the host rock and it solidifies. The new material that is formed is called lapis and contains lazurite, pyrite and calcite. Garnet, which is often red but can also be found in colors ranging from yellow to black, is formed in hot rocks that are subjected to very high pressure.
Gemstone engagement rings make an ideal alternative to diamonds. They are less expensive and can be used separately or in combination with other materials.
