Gems that form in the corundum with a titanium impurity are generally colorless. These gems are called white sapphires and can be quite beautiful. Corundum that forms with a chromium impurity is generally red in color and if it's gem quality, rubies can be made. If iron and titanium are both present, the gems that can be cut from it are blue. Colors such as yellow and purple may also be present depending on how the crystals form.
Aluminium oxide, forming into crystals is what makes corundum. It grows in several kinds of geologic formations including mica schist or marble that forms in metamorphic rock. Corundum is mined in Russia, Sri Lanka, Madagascar, Russia and India primarily, though it is found in other places as well including the United States. It is a very hard mineral, almost as hard as diamond.
Although zircon crystals are a common, less expensive substitute for diamond, white sapphires may be a better choice. Though they are rare in nature, there is less demand for them and so they are less expensive than diamonds. However, they are much harder than zircon and so are more durable.
Since the ancient Roman Empire, gems have been heat treated to either deepen the color or make pale colored gems colorless. Colorless corundum gems may then be sold as white sapphires. Heat treated gems have a reduced value because the color may fade over time.
Corundum that is less than gem quality is mined, because of its hardness, for use an abrasive. Lab grown crystals, however have been made since the 19th century. Rubies and sapphires of high quality can be grown in a lab, as well as lesser quality for industrial use. These gems are chemically indistinguishable from natural crystals. But because the process is controlled, there are few to no flaws.
In short, these gems are a rare and beautiful gem. Because of the demand for diamonds, they are a more affordable alternative when a clear gem is needed. And because they are harder than zircon, they will be more durable in a given setting.
Aluminium oxide, forming into crystals is what makes corundum. It grows in several kinds of geologic formations including mica schist or marble that forms in metamorphic rock. Corundum is mined in Russia, Sri Lanka, Madagascar, Russia and India primarily, though it is found in other places as well including the United States. It is a very hard mineral, almost as hard as diamond.
Although zircon crystals are a common, less expensive substitute for diamond, white sapphires may be a better choice. Though they are rare in nature, there is less demand for them and so they are less expensive than diamonds. However, they are much harder than zircon and so are more durable.
Since the ancient Roman Empire, gems have been heat treated to either deepen the color or make pale colored gems colorless. Colorless corundum gems may then be sold as white sapphires. Heat treated gems have a reduced value because the color may fade over time.
Corundum that is less than gem quality is mined, because of its hardness, for use an abrasive. Lab grown crystals, however have been made since the 19th century. Rubies and sapphires of high quality can be grown in a lab, as well as lesser quality for industrial use. These gems are chemically indistinguishable from natural crystals. But because the process is controlled, there are few to no flaws.
In short, these gems are a rare and beautiful gem. Because of the demand for diamonds, they are a more affordable alternative when a clear gem is needed. And because they are harder than zircon, they will be more durable in a given setting.
Comments (0)
Posting Komentar