Synthetic gemstones are almost exact copies of natural gem minerals. Made under laboratory conditions, most are manufactured by melting or dissolving the appropriate mineral ingredients and coloring agents. Then allowing the molten mass or solution to crystallize at strictly controlled pressures and temperatures. The resulting crystals are virtually identical in both composition and crystal structure to the natural gem mineral, so possess similar optical and physical properties.
The earliest gem quality synthetics were the rubies produced in 1902 by the Frenchman Auguste Verneuil using a flame fusion process. Synthetic spinels and sapphires followed soon after. This method proved so cheap and fast that it is still used to produce most synthetic rubies, sapphires, and spinels. Emeralds however are made by other processes and may take nine months to crystallize from a melt. Because of this synthetic emeralds are more expensive but may still be ten times cheaper than good natural stones. Today as technology develops it is possible to synthesize more and more gemstones including opal, chrysoberyl and diamond. Synthetic gemstones can also be used to imitat other gemstones. For instance aquamarine has long been imitated by blue synthetic spinel.
Because of the differences in their values it is essential to be able to distinguish between natural and synthetic gems. Fortunately some production methods may give rise to distinctive growth structures and inclusions such as the curved growth zones and bubbles visible in many Verneuil type synthetic or the twisted veils of fluid filled tubes in some synthetic emeralds. Many synthetic opals display a fine scaly pattern the lizard skin effect. Flawless gems however pose far greater problems so the gemmologist must resort to complex instruments and techniques such as infrared spectroscopy for the answers.
Now that you know about synthetic gems learn more about other gems at Gems Explained .