Identification of gemstones involves examining the gemstone's color, hardness and light intensity and the way the gemstone reflects light. According to the Gemological Institute of America, identification requires the use of a refractometer, a microscope and other equipment.
Observe basic characteristics
Look at the brightness and intensity of the color, and note the tone and hue. Use a jeweler's loupe to see if foreign matter appears in the stone. It may appear as a bubble, crack or crystal. Place the stone under a microscope. Certain gemstones, such as emerald or diamond, show specific types of flaws that appear clearly under magnification and make identification easier.
Run tests to determine gem properties
Measure the angle of light and its speed with a refractometer. Determine the density and hardness of a stone by measuring the specific gravity using a set of premeasured liquids. A gemstone heavier than the liquid sinks to the bottom, while a gemstone lighter than the liquid floats. A gemstone whose density matches the density of the liquid hangs suspended in the middle. Measure the intensity of light passing through a gemstone, which shows up in a characteristic rainbow pattern, with the spectrometer.
Gather and compare data on charts
Combined together, these test results compared to charts with predetermined values narrow down the type of gemstone. If no clear answer emerges, perform additional tests to supply an exact identification.